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>

server/handlers/packages.go

@@ -726,6 +726,7 @@ func (h *PackageHandler) ListEnabledSurfaces(c *gin.Context) {
 		ID    string `json:"id"`
 		Title string `json:"title"`
 		Route string `json:"route"`
+		Icon  string `json:"icon,omitempty"`
 	}
 
 	var enabled []navSurface
@@ -738,10 +739,12 @@ func (h *PackageHandler) ListEnabledSurfaces(c *gin.Context) {
 			continue
 		}
 		route, _ := p.Manifest["route"].(string)
+		icon, _ := p.Manifest["icon"].(string)
 		enabled = append(enabled, navSurface{
 			ID:    p.ID,
 			Title: p.Title,
 			Route: route,
+			Icon:  icon,
 		})
 	}
 	if enabled == nil {