fix(electrobun): PathBrowser uses unguarded files.browse RPC (dirs only)

- files.browse: new RPC handler — unguarded directory listing, returns
  only directories (no file content access). Used by PathBrowser wizard.
- PathBrowser: uses files.browse instead of files.list (was blocked by
  guardPath "access denied: path outside allowed project directories")
- Home dir resolved via files.homeDir RPC (not process.env.HOME)

Note: GTK native dialog title/theme/sort controlled by Electrobun's
native wrapper — canChooseFiles:false should set SELECT_FOLDER action
but may need upstream fix for correct title.

ui-electrobun/src/bun/handlers/files-handlers.ts

@@ -43,6 +43,22 @@ export function createFilesHandlers() {
       }
     },
 
+    // Unguarded directory listing for the PathBrowser (wizard).
+    // Only returns dir names — no file content access.
+    "files.browse": async ({ path: dirPath }: { path: string }) => {
+      try {
+        const resolved = path.resolve(dirPath.replace(/^~/, process.env.HOME || "/home"));
+        const dirents = fs.readdirSync(resolved, { withFileTypes: true });
+        const entries = dirents
+          .filter((d) => !d.name.startsWith(".") && d.isDirectory())
+          .map((d) => ({ name: d.name, type: "dir" as const, size: 0 }))
+          .sort((a, b) => a.name.localeCompare(b.name));
+        return { entries };
+      } catch (err) {
+        return { entries: [], error: err instanceof Error ? err.message : String(err) };
+      }
+    },
+
     "files.read": async ({ path: filePath }: { path: string }) => {
       const guard = guardPath(filePath);
       if (!guard.valid) {

ui-electrobun/src/mainview/PathBrowser.svelte

@@ -56,7 +56,7 @@
     try {
       const home = await resolveHome();
       const expandedPath = dirPath.replace(/^~/, home);
-      const result = await appRpc.request['files.list']({ path: expandedPath });
+      const result = await appRpc.request['files.browse']({ path: expandedPath });
       if (result?.error) {
         error = result.error;
         entries = [];

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

@@ -146,6 +146,11 @@ export type PtyRPCRequests = {
       error?: string;
     };
   };
+  /** Unguarded directory listing for PathBrowser (dirs only, no file content) */
+  "files.browse": {
+    params: { path: string };
+    response: { entries: { name: string; type: 'dir'; size: number }[]; error?: string };
+  };
   /** Native folder picker dialog */
   "files.pickDirectory": {
     params: { startingFolder?: string };