refactor(runtime,packages,examples): named constants, package enums, idiom sweep

- runtime: HEADLESS_FRAME_PATH, STICK_DEADZONE / STICK_LEFT_X/Y, key and
  byte codes as char literals throughout (`k == 'w'`, `fill(rt_map, ' ', …)`)
- ludic.gameplay/stats: drop the duplicate `stat_field` (it answered "atk"
  for every build stat); Stats.base uses stats_field_name
- ludic.shooter: compare aim modes and fire patterns with AimMode.* and
  WeaponPattern.* instead of raw ints; STICK_RIGHT_X/Y
- ludic.npcai: DecisionMade / brain_set_state use AiState.*
- examples/games/menu.ludic uses Font.load / Ui.* with FONT_PATH and
  BACKDROP named; strings.ludic header says what it prints
- whole tree: `x = x + 1` → `x += 1` (single-term right-hand sides only),
  `0 - x` → `-x`, ASCII codes → char literals; every .ludic and every
  ```ludic fence reformatted with the fixed formatter (whitespace only)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

runtime/native/query.ludic

@@ -23,7 +23,7 @@ function query_count(prop: int) -> int {
   var n = 0
   var e = world_query_next(prop, 0)
   while e >= 0 {
-    n = n + 1
+    n += 1
     e = world_query_next(prop, e + 1)
   }
   return n
@@ -40,7 +40,7 @@ function query_first(prop: int) -> int {
 # y_field); pass the same id for `prop` and `pos` to query by the position
 # component itself, or a separate tag for `prop` (e.g. "nearest Enemy").
 function query_nearest(prop: int, pos: int, x_field: int, y_field: int, px: int, py: int) -> int {
-  var best = 0 - 1
+  var best = -1
   var bestd = 0
   var e = world_query_next(prop, 0)
   while e >= 0 {