Feat v0.2.4: SDK Topbar, Schedules surface, manifest icons, UserMenu cleanup

Shell navigation:
- sw.shell.Topbar — composable nav bar (title + slot + bell + user menu)
- Topbar CSS in sw-shell.css, wired into SDK via dynamic import

Schedules surface (packages/schedules/):
- Wraps kernel /api/v1/schedules CRUD + run + logs
- Table view with cron badge, human-readable preview, enable toggle
- Create/edit dialog with live cron-to-english preview

Manifest icons:
- icon field in manifest.json (emoji string)
- Surfaces API returns icon from package manifest
- UserMenu renders per-surface icons

UserMenu cleanup:
- Removed dead Chat/Notes/Projects hardcoded links
- Menu now driven by /api/v1/surfaces API (installed surfaces only)
- Core surfaces filtered via CORE_IDS set

Bug fixes:
- isAdmin() in can.js now checks surface.admin.access RBAC grant
  instead of deprecated user.role column (v0.2.0 regression)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,40 @@
 
 All notable changes to Switchboard Core are documented here.
 
+## [Unreleased] — v0.2.4
+
+### Added
+
+- **`sw.shell.Topbar`**: Standard navigation bar component for surfaces.
+  Composes title + extension slot + NotificationBell + UserMenu into a
+  consistent 44px bar. Surfaces use `<${sw.shell.Topbar} title="...">` with
+  children rendered in the extension slot. Graceful fallback if unavailable.
+- **Schedules surface** (`packages/schedules/`): New package wrapping the
+  kernel `/api/v1/schedules` API. Table view with cron badge + human-readable
+  preview, next fire time, enable/disable toggle, manual run, and execution
+  logs panel. Create/edit dialog with live cron-to-english preview.
+- **Manifest `icon` field**: Packages can declare an emoji icon in
+  `manifest.json` (`"icon": "⏰"`). Served via the surfaces API `icon` field.
+  Rendered in the UserMenu flyout next to each surface name.
+
+### Changed
+
+- **UserMenu**: Surface list now driven entirely by the `/api/v1/surfaces`
+  API. Removed hardcoded Chat, Notes, Projects links (gutted in Phase 0).
+  Core surfaces (Admin, Settings, Team Admin, Workflow) filtered from the
+  API list and handled as dedicated menu items with RBAC gating.
+- **Tasks surface**: Replaced custom `.tasks-header` with `sw.shell.Topbar`.
+  View tabs and create button rendered in the extension slot.
+
+### Fixed
+
+- **`sw.isAdmin` RBAC regression**: `isAdmin()` in `can.js` was checking the
+  deprecated `user.role === 'admin'` field instead of the v0.2.0 RBAC grant
+  `surface.admin.access`. Admin menu item and admin-gated features now appear
+  correctly for users in the Admins group.
+
+---
+
 ## [Unreleased] — v0.2.2
 
 ### Added