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/shared/ludic.tmLanguage.json

@@ -172,12 +172,12 @@
     },
     "keyword": {
       "patterns": [
-        { "name": "keyword.control.ludic", "match": "\\b(if|else|while|for|in|match|machine|become|return|spawn|despawn|enable|disable|where|break|continue|new|try)\\b" },
+        { "name": "keyword.control.ludic", "match": "\\b(if|else|while|for|in|match|machine|prefab|become|return|spawn|despawn|enable|disable|where|break|continue|new|try)\\b" },
         { "name": "keyword.operator.logical.ludic", "match": "\\b(and|or|not)\\b" },
         { "name": "keyword.other.clause.ludic", "match": "\\b(phase|query|on)\\b" },
         { "name": "keyword.other.ludic", "match": "\\b(import|extern)\\b" },
         { "name": "storage.type.ludic", "match": "\\b(program|property|model|namespace|enum|ui|const|var|let|function|handler|entry|state|test)\\b" },
-        { "name": "support.type.primitive.ludic", "match": "\\b(int|long|fixed|bool|entity|string|pointer|byte|words|fixeds|pointers|Vector|IVec2|Rect|void)\\b" },
+        { "name": "support.type.primitive.ludic", "match": "\\b(int|long|fixed|countdown|bool|entity|string|pointer|byte|words|fixeds|pointers|Vector|IVec2|Rect|void)\\b" },
         { "name": "constant.language.boolean.ludic", "match": "\\b(true|false|null)\\b" },
         { "name": "constant.language.phase.ludic", "match": "\\b(Start|Input|FixedUpdate|Update|LateUpdate|Render)\\b" }
       ]