Scaffold sporel-module-map-editor-test

Headless test module that exercises the lib-core.maps v0.4.0 write
APIs end-to-end: load fixture map, paint cells with rotation and
auto-allocate the wall layer, set roof flags, save to a temp file,
re-load (under a patched id to dodge registry collision), and
assert state round-trips.

maps/test_work.map.json

@@ -0,0 +1,11 @@
+{
+  "schema_version": 2,
+  "id": "test_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]
+    }
+  }
+}