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>

runtime/native/input.ludic

@@ -381,6 +381,22 @@ function input_axis_i(neg: int, pos: int) -> int {
   if in_bit_get(in_held, neg) { v = v - 1 }
   return v
 }
+# The standard top-down movement intent as -1/0/1 per axis: WASD or the arrow
+# keys, and the left stick of pad 0 (past a 0.35 deadzone) when one is connected.
+function input_move_i() -> IVec2 {
+  in_init()
+  var x = input_axis_i(Key.A, Key.D) + input_axis_i(Key.Left, Key.Right)
+  var y = input_axis_i(Key.W, Key.S) + input_axis_i(Key.Up, Key.Down)
+  if input_pad_connected(0) {
+    let sx = input_pad_axis(0, 0)
+    let sy = input_pad_axis(0, 1)
+    if sx > 0.35 { x = 1 }
+    if sx < -0.35 { x = 0 - 1 }
+    if sy > 0.35 { y = 1 }
+    if sy < -0.35 { y = 0 - 1 }
+  }
+  return IVec2.make(clamp(x, 0 - 1, 1), clamp(y, 0 - 1, 1))
+}
 # A 2D vector from four direction keys, normalized so a diagonal is not faster.
 function input_vector(left: int, right: int, up: int, down: int) -> Vector {
   in_init()
@@ -412,6 +428,9 @@ function input_strength(name: pointer) -> fixed {
 #   3 confined — dissociated but visible; the mouse cannot leave the window.
 # The platform auto-releases (shows + reconnects) while the window is not key
 # (Cmd-Tab) and on close. Headless / non-windowed: a no-op.
+enum CursorMode { Normal, Hidden, Locked, Confined }   # Input.cursor_mode(mode:)
+enum PadButton { A, B, X, Y, LeftShoulder, RightShoulder, Back, Start }   # Input.bind_pad(button:) / pad_button
+enum MouseButton { Left, Right, Middle }                                  # Input.mouse_down(button:)
 function input_cursor_mode(mode: int) -> void {
   if is_windowed() { win_cursor_mode(mode) }
 }