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>

packages/ludic.gameplay/combat.ludic

@@ -53,7 +53,7 @@ var combat_pending: int = 0
   # the attacker's build: damage_pct, then a crit_pct chance to double
   var raw = amount * stats_field(src, "damage_pct", 100) / 100
   let crit = stats_field(src, "crit_pct", 0)
-  if (crit > 0) and Random.chance(percent: crit) { raw = raw * 2;  emit Crit(target: target, src: src) }
+  if (crit > 0) and Random.chance(percent: crit) { raw *= 2;  emit Crit(target: target, src: src) }
   combat_pending = combat_mitigate(target, raw)
   if emit DamageAboutToApply(target: target, src: src, amount: combat_pending) != 0 { return 0 }
   var dmg = combat_pending

packages/ludic.gameplay/faction.ludic

@@ -55,10 +55,10 @@ function fac_ensure() -> void {
 # Faction.id_of(e) — the faction id an entity carries (-1 if it has no Faction).
 @Namespace(Faction) function faction_id_of(e: int) -> int {
   let P = World.prop_id("Faction")
-  if P < 0 { return 0 - 1 }
-  if World.has(e, P) == 0 { return 0 - 1 }
+  if P < 0 { return -1 }
+  if World.has(e, P) == 0 { return -1 }
   let f = World.field_id(P, "id")
-  if f < 0 { return 0 - 1 }
+  if f < 0 { return -1 }
   return World.get(e, P, f)
 }
 

packages/ludic.gameplay/stats.ludic

@@ -89,21 +89,11 @@ model ModifierFx { Modifier }
   }
 }
 
-# map a stat code to the matching Stats field name.
-function stat_field(stat: int) -> pointer {
-  if stat == 0 { return "max_hp" }
-  if stat == 1 { return "atk" }
-  if stat == 2 { return "def" }
-  if stat == 3 { return "spd" }
-  if stat == 4 { return "max_mp" }
-  return "atk"
-}
-
 # Stats.base(e, stat) — the raw stored field, no modifiers.
 @Namespace(Stats) function stats_base(e: int, stat: int) -> int {
   let P = World.prop_id("Stats")
   if P < 0 { return 0 }
-  let f = World.field_id(P, stat_field(stat))
+  let f = World.field_id(P, stats_field_name(stat))
   if f < 0 { return 0 }
   return World.get(e, P, f)
 }
@@ -123,7 +113,7 @@ function stat_field(stat: int) -> pointer {
   while m >= 0 {
     if (World.get(m, P, ft) == e) and (World.get(m, P, fs) == stat) {
       let amt = World.get(m, P, fa)
-      if World.get(m, P, fo) == 1 { pct = pct + amt } else { flat = flat + amt }
+      if World.get(m, P, fo) == 1 { pct += amt } else { flat += amt }
     }
     m = World.query_next(P, m + 1)
   }
@@ -133,7 +123,7 @@ function stat_field(stat: int) -> pointer {
 # Stats.modify(target, stat, op, amount, ttl) — push a modifier onto the stack.
 @Namespace(Stats) function stats_modify(target: int, stat: int, op: int, amount: int, ttl: int) -> int {
   let m = World.model_id("ModifierFx")
-  if m < 0 { return 0 - 1 }
+  if m < 0 { return -1 }
   let e = World.spawn(m)
   let P = World.prop_id("Modifier")
   World.set(e, P, World.field_id(P, "target"), target)