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/components/Sidebar.tsx

@@ -56,6 +56,7 @@ import { useDialog } from "../hooks/useDialog";
 import {
   LayoutDashboard,
   FolderOpen,
+  HardDrive,
   BarChart3,
   Settings,
   Wifi,
@@ -88,6 +89,8 @@ function isUpdatePayload(x: unknown): x is UpdateStatusPayload {
 const NAV_KEYS = [
   { to: "/", icon: LayoutDashboard, key: "nav:dashboard" },
   { to: "/sessions", icon: FolderOpen, key: "nav:sessions" },
+  // The file manager (FilesPage): browse, upload and download workspace files.
+  { to: "/files", icon: HardDrive, key: "nav:files" },
 ] as const;
 
 const STORAGE_KEY = "sidebar-collapsed";