feat(engine): #90 atlas-aware Sprite component, #91 become from listeners, 0.3.x ergonomics batch

Closes the two open issues and lands the pending unreleased batch:

- #90: `Sprite { atlas: 1 }` routes esys_sprite through atlas_draw_ex
  (scale/flip/tint), so cell / cell_span / strip ids of any size draw
  through the engine sprite-render system. examples/library/sprite_atlas
  is the pixel-readback regression.
- #91: `become` from an @On(Event) listener / global handler / plain
  function no longer segfaults the compiler; it emits @L_scene_leave()
  (a dispatch on the live scene id) so the leaving scene's on-exit runs.
  UI_* handles are readable from any code (widget table built on first
  use). examples/library/scene_menus covers it.
- fix: a windowed `ludicc -o` build that reaches the audio runtime only
  through the atlas/Assets preload import now links audio.ll +
  AVFoundation (the audio backend link was gated on a game-level
  Audio.* call, so any windowed game declaring Sprite failed to link).
- the hand-written "Unreleased" CHANGELOG section is converted to
  changesets under changes/ so `x release` generates it.
- plus the batch: engine-driven retained UI + UiClicked event, Overlay
  phase, TileSkin tilemap-render system, Key.* constants, Font/Ui/File
  namespaces, Sprite.strip, prefabs, managers, countdown fields,
  enum-typed machines, layer @Queries, ludic.prefs / ludic.dungeon
  packages, Ai.seek pathing, Solids.solid2, cursor confine (mode 3)
  fix, shooter centre-aim fix, reserved-word function diagnostic.

Verified: x test (124/124), x test-tools, check-impl, check-vocabulary,
check-docs, docs-gen + docs-check, bootstrap-cfree (seed is a fixpoint).

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

tools/editors/jetbrains/src/main/kotlin/io/ludic/ide/LudicTokens.kt

@@ -49,10 +49,10 @@ object LudicVocabulary {
     )
     val STMT = setOf(
         "let", "return", "if", "else", "while", "for", "in", "spawn", "despawn",
-        "enable", "disable", "match", "machine", "state", "become", "where",
+        "enable", "disable", "match", "machine", "prefab", "state", "become", "where",
         "and", "or", "not", "break", "continue", "new", "emit", "cancel", "try"
     )
-    val PRIMITIVES = setOf("int", "long", "fixed", "bool", "entity", "string", "pointer", "byte", "words", "fixeds", "pointers", "Vector", "IVec2", "Rect", "void")
+    val PRIMITIVES = setOf("int", "long", "fixed", "countdown", "bool", "entity", "string", "pointer", "byte", "words", "fixeds", "pointers", "Vector", "IVec2", "Rect", "void")
     val PHASES = setOf("Start", "Input", "FixedUpdate", "Update", "LateUpdate", "Render")
     val WIDGETS = setOf("panel", "col", "row", "label", "button", "image", "spacer")