feat: unified group management, public groups, and activity-based sidebar

Create Group wizard (Electron-only) consolidates 6 steps across 4 interfaces
into a single multi-step page: group creation on hub, node attachment, root
selection via folder picker, GEK initialization, and auto-pairing — all in one
flow. Browser SPA keeps its current behavior unchanged.

Public group support (Option A — GEK for all groups):
- All groups have GEK regardless of visibility; open-join groups auto-admit
  via TOFU when join_policy is "open"
- Key rotation blocked for public groups (API guard + UI hidden)
- Hub signaling allows WebRTC offers for nodes hosting open-join groups even
  when the caller isn't a member yet
- attach_group writes join_policy to node.toml
- Daemon loads GEK for all groups, not just private ones
- Known-device path in join_request now auto-admits to open-join groups

Node loopback API bridge (Electron IPC):
- node:detect, node:call, node:pairing-code IPC handlers in main process
- Renderer never sees tokens, paths, or keys (session token = physical access)
- platform.js node namespace for UI consumption
- Loopback endpoints: roots CRUD, member-upload toggle, reload

Bug fixes:
- Root change detection: removed premature ctx["roots"] updates from add_root
  and remove_root that prevented indexer retarget on reload
- Duplicate offline message: global fallback now gated on !group
- Signaling membership check: fallback to open-join groups for non-members

Sidebar groups sorted by last_activity_at (most recent first):
- New Group.last_activity_at column with Alembic migration
- POST /v1/groups/{id}/activity endpoint, called on connect and chat send
- Client-side sort + throttled hub updates (1/min)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2 files changed, 33 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
index 4193f00..a8392c7 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
@@ -125,7 +125,7 @@ export default {
   // Status
   'status.idle': 'Idle',
   'status.discovering': 'Finding nodes...',
-  'status.connecting': 'Connecting via WebRTC...',
+  'status.connecting': 'Connecting...',
   'status.connecting_short': 'Connecting...',
   'status.fetching': 'Fetching index...',
   'status.files': {
@@ -332,6 +332,36 @@ export default {
   'create_group.hint': 'A group needs a node to host files. You can create the group now and connect a node later.',
   'create_group.creating': 'Creating...',
 
+  // Create Group Wizard (Electron-only)
+  'wizard.title': 'Create Group',
+  'wizard.detecting': 'Detecting local node...',
+  'wizard.node_not_found': 'No local node detected. Make sure meshbay-node is running.',
+  'wizard.retry': 'Retry',
+  'wizard.skip_node': 'Continue without node',
+  'wizard.node_offline_warning': 'Node is not running. The group will be created on the hub only. You can connect the node later from the Node page.',
+  'wizard.directories': 'Shared directories',
+  'wizard.directories_hint': 'Choose the directories this group will share. At least one is required.',
+  'wizard.add_directory': 'Add directory',
+  'wizard.upload_target': 'upload target',
+  'wizard.set_upload': 'Set as upload target',
+  'wizard.remove': 'Remove',
+  'wizard.create_and_setup': 'Create and set up',
+  'wizard.create_hub_only': 'Create on hub only',
+  'wizard.setting_up': 'Setting up your group...',
+  'wizard.step_create_hub': 'Creating group on hub',
+  'wizard.step_attach': 'Attaching to node',
+  'wizard.step_add_roots': 'Adding directories',
+  'wizard.step_gek': 'Initializing encryption key',
+  'wizard.step_pair': 'Setting up pairing',
+  'wizard.finish_later': 'Finish setup later',
+  'wizard.done_title': 'Group created',
+  'wizard.done_message': 'Your group is ready. Your node is hosting it and encryption is set up.',
+  'wizard.go_to_group': 'Go to group',
+
+  // Unified Group Settings (node sections)
+  'settings_node.roots': 'Shared directories',
+  'settings_node.detach_failed_continue': 'Could not detach the group from the node. Delete on hub anyway?',
+
   // Members
   'members.col_role': 'Role',
   'members.group_role': 'Group role',
@@ -469,6 +499,7 @@ export default {
   'node.gek_rotate_confirm': 'Rotate the group key? Connected members will receive the new key automatically. Content already downloaded is unaffected.',
   'node.gek_rotated': 'Group key rotated.',
   'node.gek_init_hint': 'No group key yet. Run GEK init from the CLI to set one up.',
+  'node.gek_public_hint': 'Key rotation is not available for public groups.',
   'node.roster': 'Roster',
   'node.roster_load': 'Load roster',
   'node.roster_empty': 'No members pinned yet.',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
index fe6c666..9eb2f30 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
@@ -125,7 +125,7 @@ export default {
   // Status
   'status.idle': 'Inactif',
   'status.discovering': 'Recherche de nodes...',
-  'status.connecting': 'Connexion via WebRTC...',
+  'status.connecting': 'Connexion…',
   'status.connecting_short': 'Connexion…',
   'status.fetching': "Récupération de l'index...",
   'status.files': {