Add window rules, real config validation, and a Wayland DRM/udev backend

- srd.rule(): match windows by title/class, apply floating/maximized/
  workspace/geometry/decoration actions on creation (crates/core/src/rules.rs)
- srd.validate_config()/srd.debug.*: real range/format checks and
  status/profiling helpers, replacing the always-true stub
- Wayland titlebar text rendering via fontdue, unit-tested without a
  display (crates/wayland/src/decoration.rs)
- Wayland precise keybinding matching, replacing the "any Super-held key"
  heuristic, sharing the keysym table with X11 (moved to
  crates/core/src/keysyms.rs)
- Wayland DRM/udev backend (crates/wayland/src/udev.rs): runs as the real
  compositor on a bare TTY via libseat/libinput/KMS, software rendering
  via Pixman + dumb buffers (no GBM/EGL required)
- srdwm_platform::detect() fix, found via VM testing: a bare TTY with no
  DISPLAY/WAYLAND_DISPLAY now correctly resolves to Wayland instead of an
  X11 backend that can never work there
- XWayland integration groundwork (crates/wayland/src/xwayland.rs): spawn,
  X11Wm, and full XwmHandler event routing into the same WindowManager/
  Space pipeline as native clients. Windows don't render yet - a real
  glamor-vs-software-renderer conflict in XWayland's own fallback path,
  root-caused via WAYLAND_DEBUG tracing and documented in
  docs/IMPLEMENTATION_STATUS.md rather than worked around blind.

All verified live in an isolated QEMU VM: X11 backend shows two
decorated, correctly-tiled xterms with real title text; the DRM/udev
Wayland backend opens the GPU, initializes input, and scans out a
rendered frame via KMS page-flip.

1 files changed, 112 insertions, 0 deletions

diff --git a/crates/core/src/keysyms.rs b/crates/core/src/keysyms.rs
new file mode 100644
index 0000000..0baa6bc
--- /dev/null
+++ b/crates/core/src/keysyms.rs
@@ -0,0 +1,112 @@
+//! A small, hand-maintained keysym <-> name table covering the keys used in
+//! practice by window-manager keybindings (letters, digits, navigation,
+//! function keys). Not a full xkbcommon-level keymap - see module docs in
+//! `lib.rs` for why that trade-off was made for this pass.
+
+pub fn keysym_to_name(keysym: u32) -> Option<String> {
+    Some(match keysym {
+        0x0020 => "Space".to_string(),
+        0x0061..=0x007a => (((keysym - 0x0061) as u8 + b'a') as char).to_string(),
+        0x0030..=0x0039 => (((keysym - 0x0030) as u8 + b'0') as char).to_string(),
+        0xff0d => "Return".to_string(),
+        0xff1b => "Escape".to_string(),
+        0xff09 => "Tab".to_string(),
+        0xff08 => "BackSpace".to_string(),
+        0xffff => "Delete".to_string(),
+        0xff51 => "Left".to_string(),
+        0xff52 => "Up".to_string(),
+        0xff53 => "Right".to_string(),
+        0xff54 => "Down".to_string(),
+        0xff55 => "Prior".to_string(),
+        0xff56 => "Next".to_string(),
+        0xff50 => "Home".to_string(),
+        0xff57 => "End".to_string(),
+        0xffbe..=0xffc9 => format!("F{}", keysym - 0xffbe + 1),
+        0x1008ff13 => "XF86AudioRaiseVolume".to_string(),
+        0x1008ff11 => "XF86AudioLowerVolume".to_string(),
+        0x1008ff12 => "XF86AudioMute".to_string(),
+        0x1008ff02 => "XF86MonBrightnessUp".to_string(),
+        0x1008ff03 => "XF86MonBrightnessDown".to_string(),
+        _ => return None,
+    })
+}
+
+/// Case-insensitive: config authors reasonably write both `"Space"` and
+/// `"space"`, and X11 key names aren't consistently capitalized in the wild.
+pub fn name_to_keysym(name: &str) -> Option<u32> {
+    match name.to_ascii_lowercase().as_str() {
+        "space" => return Some(0x0020),
+        "return" | "enter" => return Some(0xff0d),
+        "escape" => return Some(0xff1b),
+        "tab" => return Some(0xff09),
+        "backspace" => return Some(0xff08),
+        "delete" => return Some(0xffff),
+        "left" => return Some(0xff51),
+        "up" => return Some(0xff52),
+        "right" => return Some(0xff53),
+        "down" => return Some(0xff54),
+        "prior" | "pageup" => return Some(0xff55),
+        "next" | "pagedown" => return Some(0xff56),
+        "home" => return Some(0xff50),
+        "end" => return Some(0xff57),
+        "xf86audioraisevolume" => return Some(0x1008ff13),
+        "xf86audiolowervolume" => return Some(0x1008ff11),
+        "xf86audiomute" => return Some(0x1008ff12),
+        "xf86monbrightnessup" => return Some(0x1008ff02),
+        "xf86monbrightnessdown" => return Some(0x1008ff03),
+        _ => {}
+    }
+    if name.len() == 1 {
+        let c = name.chars().next().unwrap().to_ascii_lowercase();
+        if c.is_ascii_lowercase() {
+            return Some(0x0061 + (c as u32 - 'a' as u32));
+        }
+        if c.is_ascii_digit() {
+            return Some(0x0030 + (c as u32 - '0' as u32));
+        }
+    }
+    if let Some(rest) = name.to_ascii_lowercase().strip_prefix('f') {
+        if let Ok(n) = rest.parse::<u32>() {
+            if (1..=12).contains(&n) {
+                return Some(0xffbe + n - 1);
+            }
+        }
+    }
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn letters_and_digits_roundtrip() {
+        for c in 'a'..='z' {
+            let name = c.to_string();
+            let ks = name_to_keysym(&name).unwrap();
+            assert_eq!(keysym_to_name(ks), Some(name));
+        }
+        for c in '0'..='9' {
+            let name = c.to_string();
+            let ks = name_to_keysym(&name).unwrap();
+            assert_eq!(keysym_to_name(ks), Some(name));
+        }
+    }
+
+    #[test]
+    fn lowercase_names_resolve_case_insensitively() {
+        // Config authors reasonably write "Mod4+Shift+space"; this must
+        // resolve to the same keysym as "Space".
+        assert_eq!(name_to_keysym("space"), name_to_keysym("Space"));
+        assert_eq!(name_to_keysym("return"), name_to_keysym("Return"));
+        assert_eq!(name_to_keysym("f5"), name_to_keysym("F5"));
+    }
+
+    #[test]
+    fn named_keys_roundtrip() {
+        for name in ["Return", "Escape", "Tab", "Left", "Right", "Up", "Down", "F1", "F12"] {
+            let ks = name_to_keysym(name).unwrap();
+            assert_eq!(keysym_to_name(ks), Some(name.to_string()));
+        }
+    }
+}