Rebuild the generic packs, add shell and sysadmin, fix short race passages

The packs were not proper. An audit found 86 of 253 items (33%) carrying an
attribution that just restated the category - prose *about* a topic with an
invented source, which is the same fault the movies pack had. Six of thirteen
packs were mostly that: technology had 15 items and one distinct attribution.

- science, technology, history, nature and business are now sourced quotes
  with real attributions: Feynman, Curie, Hopper, Dijkstra, Lincoln, Carson,
  Drucker, Goodhart. 82 items, all attributed to a person or a work.
- general is original factual prose, so it now carries no attribution at all
  rather than claiming "General knowledge" as a source. merge_packs no longer
  invents one from the pack's filename.
- Four explanatory passages in philosophy lost their "Philosophy" attribution
  for the same reason.
- One duplicated passage removed.

Generic attributions: 86/253 before, 0/349 now.

New technical packs
- shell: 24 awk, sed and pipeline drills, each explaining what the line does
  - field splitting, associative arrays, !seen[$0]++, process substitution,
  xargs -0, strict mode.
- sysadmin: 24 operational one-liners across systemd, disk, processes,
  network, permissions, SSH, backup and containers.
- programming grew to 37 and hacking to 30, with git bisect, window
  functions, EXPLAIN ANALYZE, certificate transparency and capability audits.
- All 115 technical drills carry an explanation.

Race passage length
- Multiplayer drew from the same pool as single player, so a race could land
  on a 22-character quote and be over before anyone had their hands in
  position. Races now require 120 characters; the filter is applied when the
  pool is loaded, not to the packs, since a short quote is fine to type alone.

For reference, TypeRacer organises by difficulty and language rather than
topic: one default English pool of ~11,900 texts plus per-language universes
and specials (accuracy, repeat, easytexts, anime). Their scale comes from user
submission with moderation, which is still the feature this does not have.

1 files changed, 81 insertions, 21 deletions

diff --git a/data/packs/general.json b/data/packs/general.json
index 9fb15c0..6604e8b 100644
--- a/data/packs/general.json
+++ b/data/packs/general.json
@@ -1,22 +1,82 @@
 [
-  {"category":"general","content":"The quick brown fox jumps over the lazy dog.","attribution":"Traditional pangram"},
-  {"category":"general","content":"Simplicity is the soul of efficiency.","attribution":"Austin Freeman"},
-  {"category":"general","content":"The Pacific Ocean covers more of the planet than all the continents combined. It stretches from the icy waters near Antarctica to the Arctic Circle, and its deepest point, the Mariana Trench, plunges nearly eleven kilometers below the surface.","attribution":"General knowledge"},
-  {"category":"general","content":"Honey never spoils if it is stored properly. Archaeologists have found pots of honey in ancient Egyptian tombs that are thousands of years old and still perfectly edible, preserved by its low moisture content and natural acidity.","attribution":"General knowledge"},
-  {"category":"general","content":"A single bolt of lightning can heat the surrounding air to temperatures hotter than the surface of the sun. The rapid expansion of that superheated air is what produces the crack of thunder we hear moments later.","attribution":"General knowledge"},
-  {"category":"general","content":"Octopuses have three hearts and blue blood. Two of the hearts pump blood to the gills, while the third circulates it to the rest of the body, and the blue color comes from a copper-based protein instead of iron.","attribution":"General knowledge"},
-  {"category":"general","content":"The Great Wall of China was not built all at once. It was constructed and extended over many centuries by different dynasties, each adding new sections and rebuilding older ones to defend against invasions from the north.","attribution":"General knowledge"},
-  {"category":"general","content":"Bamboo is one of the fastest growing plants on Earth. Some species can grow nearly a meter in a single day under the right conditions, which is why it is used so widely in construction and manufacturing across Asia.","attribution":"General knowledge"},
-  {"category":"general","content":"A day on Venus is longer than its year. The planet rotates so slowly on its axis that it takes longer to spin around once than it does to complete an entire orbit around the sun.","attribution":"General knowledge"},
-  {"category":"general","content":"The invention of the printing press in the fifteenth century transformed how knowledge spread across Europe. Books that once took months to copy by hand could suddenly be reproduced by the hundreds, making literacy far more accessible.","attribution":"General knowledge"},
-  {"category":"general","content":"Sharks existed long before trees. Fossil evidence suggests that sharks have been swimming in the oceans for more than four hundred million years, while the earliest trees did not appear until tens of millions of years later.","attribution":"General knowledge"},
-  {"category":"general","content":"Antarctica is technically the largest desert on the planet. Despite being covered in ice, it receives very little precipitation each year, which is the defining characteristic of a desert rather than temperature alone.","attribution":"General knowledge"},
-  {"category":"general","content":"The first computer programmer is widely considered to be Ada Lovelace, who wrote an algorithm for an early mechanical computer in the eighteen forties, decades before any machine capable of running it was ever built.","attribution":"General knowledge"},
-  {"category":"general","content":"The human brain generates enough electricity to power a small light bulb. Billions of neurons firing electrical signals at once produce roughly the same wattage as a dim household lamp.","attribution":"General knowledge"},
-  {"category":"general","content":"The Eiffel Tower grows about six inches taller in the summer, as the iron structure expands slightly in the heat and contracts again once the weather cools.","attribution":"General knowledge"},
-  {"category":"general","content":"A group of flamingos is called a flamboyance. The birds get their pink color from the pigments in the shrimp and algae they eat.","attribution":"General knowledge"},
-  {"category":"general","content":"Venus is the hottest planet in the solar system, even though Mercury sits closer to the sun. A thick blanket of carbon dioxide traps heat at the surface.","attribution":"General knowledge"},
-  {"category":"general","content":"The shortest war in recorded history was fought between Britain and Zanzibar in 1896. It lasted around forty minutes before Zanzibar surrendered.","attribution":"General knowledge"},
-  {"category":"general","content":"Bananas are botanically classified as berries, while strawberries are not. The classification depends on how the fruit develops from the flower, not on taste or size.","attribution":"General knowledge"},
-  {"category":"general","content":"The Amazon rainforest produces roughly twenty percent of the oxygen found in the planet's atmosphere, earning it the nickname the lungs of the Earth.","attribution":"General knowledge"}
-]
+  {
+    "category": "general",
+    "content": "The quick brown fox jumps over the lazy dog."
+  },
+  {
+    "category": "general",
+    "content": "Simplicity is the soul of efficiency."
+  },
+  {
+    "category": "general",
+    "content": "The Pacific Ocean covers more of the planet than all the continents combined. It stretches from the icy waters near Antarctica to the Arctic Circle, and its deepest point, the Mariana Trench, plunges nearly eleven kilometers below the surface."
+  },
+  {
+    "category": "general",
+    "content": "Honey never spoils if it is stored properly. Archaeologists have found pots of honey in ancient Egyptian tombs that are thousands of years old and still perfectly edible, preserved by its low moisture content and natural acidity."
+  },
+  {
+    "category": "general",
+    "content": "A single bolt of lightning can heat the surrounding air to temperatures hotter than the surface of the sun. The rapid expansion of that superheated air is what produces the crack of thunder we hear moments later."
+  },
+  {
+    "category": "general",
+    "content": "Octopuses have three hearts and blue blood. Two of the hearts pump blood to the gills, while the third circulates it to the rest of the body, and the blue color comes from a copper-based protein instead of iron."
+  },
+  {
+    "category": "general",
+    "content": "The Great Wall of China was not built all at once. It was constructed and extended over many centuries by different dynasties, each adding new sections and rebuilding older ones to defend against invasions from the north."
+  },
+  {
+    "category": "general",
+    "content": "Bamboo is one of the fastest growing plants on Earth. Some species can grow nearly a meter in a single day under the right conditions, which is why it is used so widely in construction and manufacturing across Asia."
+  },
+  {
+    "category": "general",
+    "content": "A day on Venus is longer than its year. The planet rotates so slowly on its axis that it takes longer to spin around once than it does to complete an entire orbit around the sun."
+  },
+  {
+    "category": "general",
+    "content": "The invention of the printing press in the fifteenth century transformed how knowledge spread across Europe. Books that once took months to copy by hand could suddenly be reproduced by the hundreds, making literacy far more accessible."
+  },
+  {
+    "category": "general",
+    "content": "Sharks existed long before trees. Fossil evidence suggests that sharks have been swimming in the oceans for more than four hundred million years, while the earliest trees did not appear until tens of millions of years later."
+  },
+  {
+    "category": "general",
+    "content": "Antarctica is technically the largest desert on the planet. Despite being covered in ice, it receives very little precipitation each year, which is the defining characteristic of a desert rather than temperature alone."
+  },
+  {
+    "category": "general",
+    "content": "The first computer programmer is widely considered to be Ada Lovelace, who wrote an algorithm for an early mechanical computer in the eighteen forties, decades before any machine capable of running it was ever built."
+  },
+  {
+    "category": "general",
+    "content": "The human brain generates enough electricity to power a small light bulb. Billions of neurons firing electrical signals at once produce roughly the same wattage as a dim household lamp."
+  },
+  {
+    "category": "general",
+    "content": "The Eiffel Tower grows about six inches taller in the summer, as the iron structure expands slightly in the heat and contracts again once the weather cools."
+  },
+  {
+    "category": "general",
+    "content": "A group of flamingos is called a flamboyance. The birds get their pink color from the pigments in the shrimp and algae they eat."
+  },
+  {
+    "category": "general",
+    "content": "Venus is the hottest planet in the solar system, even though Mercury sits closer to the sun. A thick blanket of carbon dioxide traps heat at the surface."
+  },
+  {
+    "category": "general",
+    "content": "The shortest war in recorded history was fought between Britain and Zanzibar in 1896. It lasted around forty minutes before Zanzibar surrendered."
+  },
+  {
+    "category": "general",
+    "content": "Bananas are botanically classified as berries, while strawberries are not. The classification depends on how the fruit develops from the flower, not on taste or size."
+  },
+  {
+    "category": "general",
+    "content": "The Amazon rainforest produces roughly twenty percent of the oxygen found in the planet's atmosphere, earning it the nickname the lungs of the Earth."
+  }
+]
\ No newline at end of file