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>

backend/app/api/projects/router.py

@@ -52,7 +52,7 @@ async def list_projects_in_space(
             detail="Access denied",
         )
 
-    projects = db.query(Project).filter(Project.space_id == space_id).all()
+    projects = db.query(Project).filter(Project.space_id == space_id, Project.is_active == True).all()
 
     # Filter by project access
     accessible_projects = [p for p in projects if check_project_access(current_user, p)]
@@ -154,7 +154,7 @@ async def get_project(
     """
     Get a project by ID.
     """
-    project = db.query(Project).filter(Project.id == project_id).first()
+    project = db.query(Project).filter(Project.id == project_id, Project.is_active == True).first()
 
     if not project:
         raise HTTPException(
@@ -202,7 +202,7 @@ async def update_project(
     """
     Update a project.
     """
-    project = db.query(Project).filter(Project.id == project_id).first()
+    project = db.query(Project).filter(Project.id == project_id, Project.is_active == True).first()
 
     if not project:
         raise HTTPException(
@@ -317,7 +317,7 @@ async def list_project_statuses(
     """
     List all task statuses for a project.
     """
-    project = db.query(Project).filter(Project.id == project_id).first()
+    project = db.query(Project).filter(Project.id == project_id, Project.is_active == True).first()
 
     if not project:
         raise HTTPException(

backend/app/api/tasks/router.py

@@ -406,6 +406,28 @@ async def update_task(
     update_data = task_data.model_dump(exclude_unset=True)
     custom_values_data = update_data.pop("custom_values", None)
 
+    # Track old assignee for workload cache invalidation
+    old_assignee_id = task.assignee_id
+
+    # Validate assignee_id if provided
+    if "assignee_id" in update_data and update_data["assignee_id"]:
+        assignee = db.query(User).filter(User.id == update_data["assignee_id"]).first()
+        if not assignee:
+            raise HTTPException(
+                status_code=status.HTTP_404_NOT_FOUND,
+                detail="Assignee not found",
+            )
+
+    # Validate status_id if provided
+    if "status_id" in update_data and update_data["status_id"]:
+        from app.models.task_status import TaskStatus
+        task_status = db.query(TaskStatus).filter(TaskStatus.id == update_data["status_id"]).first()
+        if not task_status:
+            raise HTTPException(
+                status_code=status.HTTP_404_NOT_FOUND,
+                detail="Status not found",
+            )
+
     # Get the proposed start_date and due_date for validation
     new_start_date = update_data.get("start_date", task.start_date)
     new_due_date = update_data.get("due_date", task.due_date)
@@ -486,6 +508,15 @@ async def update_task(
     if "original_estimate" in update_data and task.assignee_id:
         invalidate_user_workload_cache(task.assignee_id)
 
+    # Invalidate workload cache if assignee changed
+    if "assignee_id" in update_data:
+        # Invalidate old assignee's cache
+        if old_assignee_id and old_assignee_id != task.assignee_id:
+            invalidate_user_workload_cache(old_assignee_id)
+        # Invalidate new assignee's cache
+        if task.assignee_id:
+            invalidate_user_workload_cache(task.assignee_id)
+
     # Publish real-time event
     try:
         await publish_task_event(

backend/app/api/workload/router.py

@@ -101,6 +101,10 @@ async def get_heatmap(
         None,
         description="Comma-separated list of user IDs to include"
     ),
+    hide_empty: bool = Query(
+        True,
+        description="Hide users with no tasks assigned for the week"
+    ),
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
@@ -133,8 +137,10 @@ async def get_heatmap(
 
     week_start, week_end = get_week_bounds(week_start)
 
-    # Try cache first
-    cached = get_cached_heatmap(week_start, department_id, accessible_user_ids)
+    # Try cache first (only use cache for default hide_empty=True)
+    cached = None
+    if hide_empty:
+        cached = get_cached_heatmap(week_start, department_id, accessible_user_ids)
     if cached:
         return WorkloadHeatmapResponse(
             week_start=week_start,
@@ -148,10 +154,12 @@ async def get_heatmap(
         week_start=week_start,
         department_id=department_id,
         user_ids=accessible_user_ids,
+        hide_empty=hide_empty,
     )
 
-    # Cache the result
-    set_cached_heatmap(week_start, summaries, department_id, accessible_user_ids)
+    # Cache the result (only cache when hide_empty=True, the default)
+    if hide_empty:
+        set_cached_heatmap(week_start, summaries, department_id, accessible_user_ids)
 
     return WorkloadHeatmapResponse(
         week_start=week_start,