fix(map-editor): v0.2.0b.1 — bind blob_rect_stone material so Auto-Tile renders

work.map.json was still schema-v2 with the legacy fa_terrain_v1
atlas — neither has a `material` field on its layers, so the
renderer's vertex/blob path never fired and Auto-Tile painting had
no visible effect (the set_vertex writes landed but the renderer
fell back to the cell-tile path that doesn't consume them).

Migration:
 - schema_version 2 -> 3
 - size 4x4 -> 16x16 (room to paint)
 - atlases: fa_terrain_v1 -> blob_rect_stone (S-V2E2-RM-Blob 14-slot
   atlas from lib-asset.prototype-blob-geom)
 - layers: surface + wall, both with "material": "blob_rect_stone";
   vertices+overrides start empty (lib-core.maps lazy-allocates on
   first set_vertex)

Manifest:
 - asset_aliases: fa_terrain_v1 -> blob_rect_stone (lib-asset.
   prototype-blob-geom)
 - deps: drop prototype-fa-starter, add prototype-blob-geom 0.1.0

maps/work.map.json

@@ -1,11 +1,10 @@
 {
-  "schema_version": 2,
-  "id": "work",
-  "size": { "w": 4, "h": 4 },
-  "atlases": ["fa_terrain_v1"],
-  "layers": {
-    "surface": {
-      "tiles": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
+    "schema_version": 3,
+    "id": "work",
+    "size": { "w": 16, "h": 16 },
+    "atlases": [ "blob_rect_stone" ],
+    "layers": {
+        "surface": { "material": "blob_rect_stone" },
+        "wall":    { "material": "blob_rect_stone" }
     }
-  }
 }