feat(engine): Tiled P3 — animated tiles (deterministic frame clock) + tile objects (#71)

- Animated tiles: a tileset <animation>'s {tileid, duration} frames advance as a
  pure function of the fixed 60/s engine frame counter (the same clock SpriteAnim
  rides), so an animated GID resolves at draw to the current frame's GID with its
  flip flags preserved — deterministic, frame-identical across runs, ticks for
  free. Tiled.frame_gid(map, gid, frame) / Tiled.animated(map, gid) expose it;
  Tiled.draw_anim(map, camx, camy, frame) draws a map with animations advanced.
- Tile objects: object-layer entries with a `gid` draw the tile image (with their
  own flip flags), bottom-anchored at the object position, as placeable sprites;
  tmap_draw_full now renders object layers alongside tile layers.

Proven by library/tiled_p3.ludic (14 assertions): frame advance at authored
durations + wrap, flip flags riding an animation swap, tile-object parse + draw +
flip mirroring, and the design's named rpg/beach_tileset.tsx (33 <animation>
blocks / 131 frames). x test: 94 passed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

assets/tiled-fixtures/anim_map.tmx

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Hand-authored P3 fixture: animated tile + tile object (issue #71). CC0. -->
+<map version="1.10" tiledversion="1.10.2" orientation="orthogonal" renderorder="right-down" width="4" height="4" tilewidth="16" tileheight="16" infinite="0" nextlayerid="3" nextobjectid="2">
+ <tileset firstgid="1" source="anim_tiles.tsx"/>
+ <layer id="1" name="bg" width="4" height="4">
+  <data encoding="csv">
+1,0,0,0,
+0,0,0,0,
+0,0,0,0,
+0,0,0,0
+</data>
+ </layer>
+ <objectgroup id="2" name="objects">
+  <object id="1" gid="53" x="16" y="32" width="16" height="16"/>
+ </objectgroup>
+</map>