feat: v2.7.7 — File Explorer on workspaces and the user's home, clone with per-user git identity

- File Explorer (Files in the sidebar, /files; also from a workspace's Files
  tab, portalled so no panel clips it), laid out like GNOME Files: places
  (Home, workspaces, Trash), Back/Forward/Up, path bar, search, icon grid with
  image thumbnails or list, labelled New/Upload, selection action bar, hidden
  files behind Ctrl+H, right-click menus and the usual keys.
  Make, rename, move, copy (within a workspace, between workspaces, home ↔
  workspace), delete into a per-account trash restorable for 7 days, streamed
  upload of files and whole folders (≤ 500 MB a batch, Replace / Keep both /
  Skip on a taken name), download a file or a zip of anything.
  server/lib/file-explorer.js, /api/lanes/:id/fs/*, /api/homes/:who/fs/*.
- The user's home: every dot entry at its top stays hidden and refused
  (also via a symlink, download, zip or as a copy source); an admin may view
  other users' homes read-only, audited.
- write-as learns move/copy (re-run `sudo agenthub server install-system`).
- Hardening: a write to a workspace re-checks its owner by the live role;
  S3 keeps its server.conf if the file stops reading and a tmux call never
  falls back to the host's server; the AI Proxy gateway marks what it relays
  and the dashboard refuses it; a NUL in a pane's argv/env is refused.
- OpenAPI for the new routes (server/openapi-extra/files.js); docs (API,
  SERVER-MODE, CLAUDE.md) updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

client/src/App.tsx

@@ -87,6 +87,7 @@ const SessionDetail = lazy(() =>
 const SnapshotView = lazy(() =>
   import("./pages/SnapshotView").then((m) => ({ default: m.SnapshotView }))
 );
+const FilesPage = lazy(() => import("./pages/FilesPage").then((m) => ({ default: m.FilesPage })));
 const Users = lazy(() => import("./pages/Users").then((m) => ({ default: m.Users })));
 
 function PageFallback() {
@@ -210,6 +211,14 @@ export default function App() {
                 </Page>
               }
             />
+            <Route
+              path="files"
+              element={
+                <Page>
+                  <FilesPage />
+                </Page>
+              }
+            />
             <Route
               path="users"
               element={