feat: complete LOW priority code quality improvements

Backend:
- LOW-002: Add Query validation with max page size limits (100)
- LOW-003: Replace magic strings with TaskStatus.is_done flag
- LOW-004: Add 'creation' trigger type validation
- Add action_executor.py with UpdateFieldAction and AutoAssignAction

Frontend:
- LOW-005: Replace TypeScript 'any' with 'unknown' + type guards
- LOW-006: Add ConfirmModal component with A11Y support
- LOW-007: Add ToastContext for user feedback notifications
- LOW-009: Add Skeleton components (17 loading states replaced)
- LOW-010: Setup Vitest with 21 tests for ConfirmModal and Skeleton

Components updated:
- App.tsx, ProtectedRoute.tsx, Spaces.tsx, Projects.tsx, Tasks.tsx
- ProjectSettings.tsx, AuditPage.tsx, WorkloadPage.tsx, ProjectHealthPage.tsx
- Comments.tsx, AttachmentList.tsx, TriggerList.tsx, TaskDetailModal.tsx
- NotificationBell.tsx, BlockerDialog.tsx, CalendarView.tsx, WorkloadUserDetail.tsx

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

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

backend/app/schemas/task.py

@@ -1,4 +1,4 @@
-from pydantic import BaseModel
+from pydantic import BaseModel, computed_field
 from typing import Optional, List, Any, Dict
 from datetime import datetime
 from decimal import Decimal
@@ -79,6 +79,12 @@ class TaskResponse(TaskBase):
     class Config:
         from_attributes = True
 
+    # Alias for original_estimate for frontend compatibility
+    @computed_field
+    @property
+    def time_estimate(self) -> Optional[Decimal]:
+        return self.original_estimate
+
 
 class TaskWithDetails(TaskResponse):
     assignee_name: Optional[str] = None

backend/app/schemas/trigger.py

@@ -28,9 +28,23 @@ class TriggerCondition(BaseModel):
 
 
 class TriggerAction(BaseModel):
-    type: str = Field(default="notify", description="Action type: notify")
-    target: str = Field(default="assignee", description="Target: assignee, creator, project_owner, user:<id>")
+    """Action configuration for triggers.
+
+    Supported action types:
+    - notify: Send notification (requires target, optional template)
+    - update_field: Update task field (requires field, value)
+    - auto_assign: Auto-assign task (requires strategy, optional user_id for specific_user)
+    """
+    type: str = Field(..., description="Action type: notify, update_field, auto_assign")
+    # Notify action fields
+    target: Optional[str] = Field(None, description="Target: assignee, creator, project_owner, user:<id>")
     template: Optional[str] = Field(None, description="Message template with variables")
+    # update_field action fields (FEAT-014)
+    field: Optional[str] = Field(None, description="Field to update: priority, status_id, due_date")
+    value: Optional[Any] = Field(None, description="New value for the field")
+    # auto_assign action fields (FEAT-015)
+    strategy: Optional[str] = Field(None, description="Strategy: round_robin, least_loaded, specific_user")
+    user_id: Optional[str] = Field(None, description="User ID for specific_user strategy")
 
 
 class TriggerCreate(BaseModel):