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/App.tsx

@@ -7,6 +7,7 @@ import Spaces from './pages/Spaces'
 import Projects from './pages/Projects'
 import Tasks from './pages/Tasks'
 import ProjectSettings from './pages/ProjectSettings'
+import MySettings from './pages/MySettings'
 import AuditPage from './pages/AuditPage'
 import WorkloadPage from './pages/WorkloadPage'
 import ProjectHealthPage from './pages/ProjectHealthPage'
@@ -111,6 +112,16 @@ function App() {
           </ProtectedRoute>
         }
       />
+      <Route
+        path="/my-settings"
+        element={
+          <ProtectedRoute>
+            <Layout>
+              <MySettings />
+            </Layout>
+          </ProtectedRoute>
+        }
+      />
     </Routes>
   )
 }