Bump dep on lib-core.maps to 0.3.0

Required after the maps lib's 0.3.0 rewrite for paired-PNG atlases.
rts-prototype's legacy *.tilemap.json color-only fixture still loads
fine through the v1 auto-upgrade path; rendering uses render-lib's
color-rect draw_map and does not require atlas textures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

manifest.module

@@ -6,7 +6,7 @@
     "ci_frames": 60,
     "entry_point": "init.lua",
     "deps": [
-        {"id": "lib-core.maps",      "version": "0.2.0"},
+        {"id": "lib-core.maps",      "version": "0.3.0"},
         {"id": "lib-core.render",    "version": "0.1.0"},
         {"id": "lib-core.camera",    "version": "0.3.0"},
         {"id": "lib-core.input",     "version": "0.4.0"},