feat: implement soft delete, task editing fixes, and UI improvements

Backend:
- Add soft delete for spaces and projects (is_active flag)
- Add status_id and assignee_id to TaskUpdate schema
- Fix task PATCH endpoint to update status and assignee
- Add validation for assignee_id and status_id in task updates
- Fix health service to count tasks with "Blocked" status as blockers
- Filter out deleted spaces/projects from health dashboard
- Add workload cache invalidation on assignee changes

Frontend:
- Add delete confirmation dialogs for spaces and projects
- Fix UserSelect to display selected user name (valueName prop)
- Fix task detail modal to refresh data after save
- Enforce 2-level subtask depth limit in UI
- Fix timezone bug in date formatting (use local timezone)
- Convert NotificationBell from Tailwind to inline styles
- Add i18n translations for health, workload, settings pages
- Add parent_task_id to Task interface across components

OpenSpec:
- Archive add-delete-capability change

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/contexts/NotificationContext.tsx

@@ -192,7 +192,9 @@ export function NotificationProvider({ children }: { children: ReactNode }) {
     isMountedRef.current = true
     const token = localStorage.getItem('token')
     if (token) {
+      // Fetch both unread count and initial notifications
       refreshUnreadCount()
+      fetchNotifications()
       // Delay WebSocket connection to avoid StrictMode race condition
       const connectTimeout = setTimeout(() => {
         if (isMountedRef.current) {
@@ -219,7 +221,7 @@ export function NotificationProvider({ children }: { children: ReactNode }) {
     return () => {
       isMountedRef.current = false
     }
-  }, [refreshUnreadCount, connectWebSocket])
+  }, [refreshUnreadCount, fetchNotifications, connectWebSocket])
 
   return (
     <NotificationContext.Provider