Scaffold sporel-module-map-editor package

Empty launchable module with deps on lib-core.maps 0.4.0, render,
camera, input, and the fa_terrain_v1 asset alias. Renders the
default 4x4 empty work-map; interactive editing wired in
subsequent commits.

README.md

@@ -0,0 +1,15 @@
+# sporel-module-map-editor
+
+Interactive map editor module for v2 Sporel maps. Click-to-paint, vertical layer-chip overlay, collapsible atlas+tile picker.
+
+## Status
+
+`v0.1.0` — initial POC. See `docs/superpowers/specs/2026-05-23-sporel-module-map-editor-design.md` in `sporel-meta` for the full spec.
+
+## Run
+
+```bash
+bash scripts/run-map-editor.sh [target_map.json]
+```
+
+(Detailed hotkey reference and UI walkthrough added in a later commit.)