Convert public directory from submodule to normal directory

- Remove public from git submodule tracking
- Add all public directory contents as regular files
- Fixes GitHub Actions error: "No url found for submodule path 'public' in .gitmodules"

🤖 Generated with [Claude Code](https://claude.ai/code)

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

public/planet/asset-manifest.json

@@ -0,0 +1,12 @@
+{
+  "files": {
+    "main.css": "/static/css/main.778b1327.css",
+    "main.js": "/static/js/main.85974979.js",
+    "static/js/206.650ab1fe.chunk.js": "/static/js/206.650ab1fe.chunk.js",
+    "index.html": "/index.html"
+  },
+  "entrypoints": [
+    "static/css/main.778b1327.css",
+    "static/js/main.85974979.js"
+  ]
+}