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/ludic-tools/lsp.ludic

@@ -204,7 +204,7 @@ program LudicLsp {
     return c == 43 or c == 45 or c == 42 or c == 47 or c == 37 or c == 60 or c == 62 or c == 61 or c == 40 or c == 41 or c == 123 or c == 125 or c == 91 or c == 93 or c == 44 or c == 58 or c == 46 or c == 33 or c == 64 or c == 59
   }
   function is_type_word(w: pointer) -> bool {
-    return (w == "int") or (w == "long") or (w == "fixed") or (w == "bool") or (w == "entity") or (w == "string") or (w == "pointer") or (w == "byte") or (w == "words") or (w == "fixeds") or (w == "pointers") or (w == "Vector") or (w == "IVec2") or (w == "Rect") or (w == "void")
+    return (w == "int") or (w == "long") or (w == "fixed") or (w == "countdown") or (w == "bool") or (w == "entity") or (w == "string") or (w == "pointer") or (w == "byte") or (w == "words") or (w == "fixeds") or (w == "pointers") or (w == "Vector") or (w == "IVec2") or (w == "Rect") or (w == "void")
   }
   function is_phase_word(w: pointer) -> bool {
     return (w == "Start") or (w == "Input") or (w == "FixedUpdate") or (w == "Update") or (w == "LateUpdate") or (w == "Render")
@@ -214,7 +214,7 @@ program LudicLsp {
     if (w == "const") or (w == "var") or (w == "function") or (w == "extern") or (w == "handler") or (w == "entry") or (w == "event") or (w == "scene") { return true }
     if (w == "phase") or (w == "query") or (w == "on") or (w == "cancellable") or (w == "public") or (w == "layer") or (w == "start") { return true }
     if (w == "let") or (w == "return") or (w == "if") or (w == "else") or (w == "while") or (w == "for") or (w == "in") or (w == "spawn") or (w == "despawn") { return true }
-    if (w == "enable") or (w == "disable") or (w == "match") or (w == "machine") or (w == "state") or (w == "become") or (w == "where") { return true }
+    if (w == "enable") or (w == "disable") or (w == "match") or (w == "machine") or (w == "state") or (w == "become") or (w == "where") or (w == "prefab") { return true }
     if (w == "and") or (w == "or") or (w == "not") or (w == "break") or (w == "continue") or (w == "new") or (w == "emit") or (w == "cancel") { return true }
     return false
   }