feat(hub): split the group UI into a pluggable "applications" architecture

GroupPage's 6620-line app.js carried Chat and Files wedged in directly, with
no way to add another group-level app without touching the shell itself. It
is now app.js (routing, non-group pages) plus nine focused files — apps.js
(the registry), chat-app.js, files-app.js, video-player.js, group-page.js
(the shell), group-settings.js, hub-client.js, icon.js and file-utils.js —
with docs/apps.md as the checklist for adding one (Videos/Music/Photos are
sketched there, not built).

Node side gained the matching enablement mechanism, mirroring
member_upload exactly: a roster setting, a signed apps_enabled op enforced
by _has_admin_authority, exposed in the handshake ack. Operators toggle
applications per group from Settings, which also gained a small reorder:
Invite, Pairing, Applications, Shared directories, Uploads, danger zone,
Your devices, Members.

Two bugs surfaced during the split, both missing an import across the new
file boundary and invisible to node --check or a module-load probe since
they only throw when the code path actually runs:

- group-page.js called onRefreshAuth on a stale-token handshake rejection,
  but app.js never imported refreshAccessToken from hub-client.js — so a
  brand new member (including a group's own creator) hit "Not a member of
  this group" and the retry silently failed, throwing before it could
  refresh the token.
- chat-app.js called getLocale() for message timestamps without importing
  it from i18n.js. Opening Chat on a group with real messages threw mid-
  render; uncaught, that appears to wedge Preact's render scheduler, so
  every button on the page stopped responding until reload.

Caught the second class of bug with a proper no-undef audit across all
split files (a temporarily installed ESLint 9, since the system one is too
old to parse this codebase's syntax) rather than trusting grep. 827 tests
pass; 6 new ones cover the apps_enabled policy.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016SF6RKNBKg9qejmoMJ9ybA

1 files changed, 28 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/apps.js b/packages/meshbay-hub/src/meshbay_hub/static/apps.js
new file mode 100644
index 0000000..0db713c
--- /dev/null
+++ b/packages/meshbay-hub/src/meshbay_hub/static/apps.js
@@ -0,0 +1,28 @@
+import { ChatPanel } from './chat-app.js';
+import { FilesPanel } from './files-app.js';
+
+/**
+ * Every group "application", in tab order.
+ *
+ * Adding one (Videos, Music, Photos — none of them need an MNP change, see
+ * the node's indexer classifying video/audio/image already) means a new file
+ * exporting a component and one entry here. Nothing in group-page.js changes:
+ * every registered component receives the same shared context (see its
+ * `commonProps`) and renders itself into the active tab.
+ *
+ * `key` doubles as the identifier the node's `apps_enabled` setting uses, so
+ * it must match `ALLOWED_APPS` in the node's webrtc_server.py.
+ */
+const APPS = [
+  { key: 'chat', icon: 'chat', labelKey: 'group.tab_chat', Component: ChatPanel },
+  { key: 'files', icon: 'folder', labelKey: 'group.tab_files', Component: FilesPanel },
+];
+
+/** The registry filtered to what this group has enabled, in registry order. */
+function visibleApps(enabledKeys) {
+  const enabled = new Set(
+    enabledKeys && enabledKeys.length ? enabledKeys : APPS.map(a => a.key));
+  return APPS.filter(a => enabled.has(a.key));
+}
+
+export { APPS, visibleApps };