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>

examples/games/chronorift/rules.ludic

@@ -15,7 +15,7 @@ function walkable(x: int, y: int) -> bool {
   let c = Map.tile(x, y)
   return c == '.' or c == 'D' or c == 'r' or c == ',' or c == 'S' or c == 'B' or c == 'h'
 }
-function is_confirm(k: int) -> bool { return k == 32 or k == 10 or k == 13 }
+function is_confirm(k: int) -> bool { return k == ' ' or k == '\n' or k == '\r' }
 function enemy_name(et: int) -> string {
   if et == 0 { return "SLIME" }
   if et == 1 { return "SKELETON" }
@@ -70,15 +70,15 @@ function build_dungeon(x: int) -> int {
 function grant_xp(amount: int) -> int {
   for (t) in query [Stats, {Party}] {
     if t.hp > 0 {
-      t.xp = t.xp + amount
+      t.xp += amount
       while t.xp >= t.lvl * 20 {
         t.xp = t.xp - t.lvl * 20
-        t.lvl = t.lvl + 1
-        t.maxhp = t.maxhp + 8
+        t.lvl += 1
+        t.maxhp += 8
         t.hp = t.maxhp
-        t.maxmp = t.maxmp + 2
-        t.atk = t.atk + 2
-        t.def = t.def + 1
+        t.maxmp += 2
+        t.atk += 2
+        t.def += 1
       }
     }
   }