feat(engine): Tiled P1 — rt_tmap model + GID resolver + render + projection (#69)

The heart of Tiled support: load a map and draw it.

- rt_tmap model (Tmap/TmLayer/TmTileset in tiled.ludic): map header + ordered
  layers (dense int32 GID arrays, heap-allocated to w*h, lifting the 96x64 cap)
  + tilesets. Built from the intermediate Value tree, so the TMX and TMJ paths
  both feed it.
- GID resolver (Tiled.resolve): gid -> (tileset, localId, flipH/V/D); the three
  flip flags masked off before the local-id lookup, returned alongside. gid==0
  is empty.
- Image-backed render (Tiled.draw): every visible tile layer in file order,
  blitting each tile from its tileset image with flips applied at draw.
- Compatibility projection (Tiled.project / auto on load): a designated
  collision layer projects to the legacy byte tilemap ('#' solid, '=' one-way
  via the oneway property, ' ' empty) so Grid.*/Path.*/esys_move are unchanged.
- Tiled.load resolves external tilesets + images relative to the map file and
  auto-projects a collision/solids/walls layer.
- The grid and physics_tiles demos now run off a loaded map (grid_maze.tmx /
  physics_map.tmx) instead of hand-authored Map.row strings, byte-identically.

Two compiler fixes fell out of this (see the changeset):
- emit_index_addr set g_addr_ty before evaluating the index, so slice[obj.field]
  came back mis-typed; set it last, like the raw-pointer branches.
- @strcmp was declared by both the world table and the fs prelude; centralise
  it in the head prelude so a game that uses Fs/Path links.

Proven by library/tiled_p1.ludic (14 assertions: loads+renders Kenney map
identically from .tmx and .tmj, flip mirroring) + the converted grid/
physics_tiles demos. x test: 92 passed; self-host bootstrap fixpoint intact.

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

selfhost/backend/emit_call.ludic

@@ -611,8 +611,19 @@ function emit_ns_call(ns: pointer, meth: pointer, e: Node) -> Val {
   # read/read_tsx produce the intermediate Value tree (#68); load/gid/resolve/
   # draw/prop operate on the loaded map model (#69+).
   if (ns == "Tiled") {
-    if (meth == "read")      { bare = "tiled_read";      push(labels, "path") }
-    if (meth == "read_tsx")  { bare = "tiled_read_tsx";  push(labels, "path") }
+    if (meth == "read")        { bare = "tiled_read";        push(labels, "path") }
+    if (meth == "read_tsx")    { bare = "tiled_read_tsx";    push(labels, "path") }
+    if (meth == "load")        { bare = "tiled_load";        push(labels, "path") }
+    if (meth == "gid")         { bare = "tmap_gid";          push(labels, "map"); push(labels, "layer"); push(labels, "x"); push(labels, "y") }
+    if (meth == "resolve")     { bare = "tmap_resolve";      push(labels, "map"); push(labels, "gid") }
+    if (meth == "width")       { bare = "tmap_width";        push(labels, "map") }
+    if (meth == "height")      { bare = "tmap_height";       push(labels, "map") }
+    if (meth == "layer_count") { bare = "tmap_layer_count";  push(labels, "map") }
+    if (meth == "layer_name")  { bare = "tmap_layer_name";   push(labels, "map"); push(labels, "index") }
+    if (meth == "draw")        { bare = "tmap_draw";         push(labels, "map"); push(labels, "camx"); push(labels, "camy") }
+    if (meth == "project")     { bare = "tmap_project";      push(labels, "map"); push(labels, "layer") }
+    if (meth == "tree")        { bare = "tmap_tree";         push(labels, "map") }
+    if (meth == "tile_prop")   { bare = "tmap_tile_prop";    push(labels, "map"); push(labels, "gid"); push(labels, "name") }
   }
   # #62: a package-provided namespace (declared with @Namespace(Foo)) that none
   # of the hardcoded core blocks matched — alias Foo.method to the bare function