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, 20 insertions, 15 deletions

diff --git a/data/packs/nature.json b/data/packs/nature.json
index 4bb274f..3764339 100644
--- a/data/packs/nature.json
+++ b/data/packs/nature.json
@@ -1,17 +1,22 @@
 [
-  {"category":"nature","content":"The world is big and I want to have a good look at it before it gets dark.","attribution":"John Muir"},
-  {"category":"nature","content":"In every walk with nature one receives far more than he seeks.","attribution":"John Muir"},
-  {"category":"nature","content":"Heaven is under our feet as well as over our heads.","attribution":"Henry David Thoreau, Walden"},
-  {"category":"nature","content":"The Amazon rainforest is home to an estimated ten percent of all known species on Earth, making it one of the most biodiverse regions on the planet.","attribution":"Nature"},
-  {"category":"nature","content":"Coral reefs cover less than one percent of the ocean floor, yet they support roughly a quarter of all marine species.","attribution":"Nature"},
-  {"category":"nature","content":"Migratory birds can travel thousands of miles between breeding and wintering grounds, navigating using the sun, stars, and the Earth's magnetic field.","attribution":"Nature"},
-  {"category":"nature","content":"A single mature tree can absorb around twenty two kilograms of carbon dioxide per year, making forests an important part of regulating the planet's climate.","attribution":"Nature"},
-  {"category":"nature","content":"Bees pollinate roughly a third of the crops humans rely on for food, making them essential to global agriculture despite their small size.","attribution":"Nature"},
-  {"category":"nature","content":"The deepest part of the ocean, the Mariana Trench, plunges nearly eleven kilometers below the surface, deeper than Mount Everest is tall.","attribution":"Nature"},
-  {"category":"nature","content":"Deserts are defined by low precipitation rather than temperature, which is why some of the coldest places on Earth, including parts of Antarctica, are technically deserts.","attribution":"Nature"},
-  {"category":"nature","content":"Mycorrhizal fungi form partnerships with the roots of most plants, helping them absorb water and nutrients in exchange for sugars produced by photosynthesis.","attribution":"Nature"},
-  {"category":"nature","content":"Wolves live and hunt in structured packs, usually led by a breeding pair, and communicate through howls that can be heard for several kilometers.","attribution":"Nature"},
-  {"category":"nature","content":"The Sahara Desert was once a green landscape with lakes and grasslands, before a shift in the Earth's orbit altered rainfall patterns thousands of years ago.","attribution":"Nature"},
-  {"category":"nature","content":"Rivers shape the landscape around them over thousands of years, carving canyons and depositing sediment that forms fertile floodplains.","attribution":"Nature"},
-  {"category":"nature","content":"A rainforest canopy can be so dense that less than two percent of sunlight reaches the forest floor below.","attribution":"Nature"}
+  {"category":"nature","attribution":"John Muir","content":"In every walk with nature one receives far more than he seeks."},
+  {"category":"nature","attribution":"John Muir, My First Summer in the Sierra","content":"When we try to pick out anything by itself, we find it hitched to everything else in the universe."},
+  {"category":"nature","attribution":"John Muir","content":"The mountains are calling and I must go."},
+  {"category":"nature","attribution":"Rachel Carson, Silent Spring","content":"In nature nothing exists alone."},
+  {"category":"nature","attribution":"Rachel Carson, The Sense of Wonder","content":"Those who contemplate the beauty of the earth find reserves of strength that will endure as long as life lasts."},
+  {"category":"nature","attribution":"Henry David Thoreau, Walden","content":"I went to the woods because I wished to live deliberately, to front only the essential facts of life."},
+  {"category":"nature","attribution":"Henry David Thoreau, Walking","content":"In wildness is the preservation of the world."},
+  {"category":"nature","attribution":"Aldo Leopold, A Sand County Almanac","content":"A thing is right when it tends to preserve the integrity, stability and beauty of the biotic community."},
+  {"category":"nature","attribution":"Aldo Leopold, A Sand County Almanac","content":"There are some who can live without wild things, and some who cannot."},
+  {"category":"nature","attribution":"David Attenborough","content":"It seems to me that the natural world is the greatest source of excitement, of visual beauty, of intellectual interest."},
+  {"category":"nature","attribution":"David Attenborough","content":"No one will protect what they don't care about, and no one will care about what they have never experienced."},
+  {"category":"nature","attribution":"Ralph Waldo Emerson, Nature","content":"In the woods, we return to reason and faith. There I feel that nothing can befall me in life which nature cannot repair."},
+  {"category":"nature","attribution":"Mary Oliver","content":"Tell me, what is it you plan to do with your one wild and precious life?"},
+  {"category":"nature","attribution":"Wendell Berry","content":"The earth is what we all have in common."},
+  {"category":"nature","attribution":"Robin Wall Kimmerer, Braiding Sweetgrass","content":"In some Native languages the term for plants translates to those who take care of us."},
+  {"category":"nature","attribution":"Charles Darwin, The Voyage of the Beagle","content":"The land is one great wild, untidy, luxuriant hothouse, made by nature for herself."},
+  {"category":"nature","attribution":"Gerard Manley Hopkins, God's Grandeur","content":"There lives the dearest freshness deep down things."},
+  {"category":"nature","attribution":"Gary Snyder","content":"Nature is not a place to visit. It is home."},
+  {"category":"nature","attribution":"Edward Abbey, Desert Solitaire","content":"Wilderness is not a luxury but a necessity of the human spirit."},
+  {"category":"nature","attribution":"Chief Seattle","content":"The earth does not belong to us. We belong to the earth."}
 ]