fix(electrobun): native folder picker dialog replaces inline PathBrowser

- Uses Electrobun's Utils.openFileDialog (canChooseDirectory: true)
- files.pickDirectory + files.homeDir RPC handlers
- ProjectWizard: 📂 button opens native OS dialog
- Removed broken inline PathBrowser (process.env.HOME not in WebView)

ui-electrobun/src/shared/pty-rpc-schema.ts

@@ -146,6 +146,16 @@ export type PtyRPCRequests = {
       error?: string;
     };
   };
+  /** Native folder picker dialog */
+  "files.pickDirectory": {
+    params: { startingFolder?: string };
+    response: { path: string | null };
+  };
+  /** Get home directory path */
+  "files.homeDir": {
+    params: {};
+    response: { path: string };
+  };
   /** Write text content to a file (atomic temp+rename). */
   "files.write": {
     params: { path: string; content: string };