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/services/trigger_service.py

@@ -1,9 +1,17 @@
 import uuid
+import logging
 from typing import List, Dict, Any, Optional
 from sqlalchemy.orm import Session
 
 from app.models import Trigger, TriggerLog, Task, User, Project
 from app.services.notification_service import NotificationService
+from app.services.action_executor import (
+    ActionExecutor,
+    ActionExecutionError,
+    ActionValidationError,
+)
+
+logger = logging.getLogger(__name__)
 
 
 class TriggerService:
@@ -74,23 +82,78 @@ class TriggerService:
         old_values: Dict[str, Any],
         new_values: Dict[str, Any],
     ) -> TriggerLog:
-        """Execute trigger actions and log the result."""
+        """Execute trigger actions and log the result.
+
+        Uses a database savepoint to ensure atomicity - if any action fails,
+        all previously executed actions within this trigger are rolled back.
+        """
         actions = trigger.actions if isinstance(trigger.actions, list) else [trigger.actions]
         executed_actions = []
         error_message = None
 
+        # Build execution context
+        context = {
+            "old_values": old_values,
+            "new_values": new_values,
+            "current_user": current_user,
+            "trigger": trigger,
+        }
+
+        # Use savepoint for transaction atomicity - if any action fails,
+        # all changes made by previous actions will be rolled back
+        savepoint = db.begin_nested()
         try:
             for action in actions:
                 action_type = action.get("type")
+
+                # Handle built-in notify action
                 if action_type == "notify":
                     TriggerService._execute_notify_action(db, action, task, current_user, old_values, new_values)
                     executed_actions.append({"type": action_type, "status": "success"})
 
+                # Handle update_field action (FEAT-014)
+                elif action_type == "update_field":
+                    result = ActionExecutor.execute_action(db, task, action, context)
+                    if result:
+                        executed_actions.append(result)
+                        logger.info(
+                            f"Trigger '{trigger.name}' executed update_field: "
+                            f"field={result.get('field')}, new_value={result.get('new_value')}"
+                        )
+
+                # Handle auto_assign action (FEAT-015)
+                elif action_type == "auto_assign":
+                    result = ActionExecutor.execute_action(db, task, action, context)
+                    if result:
+                        executed_actions.append(result)
+                        logger.info(
+                            f"Trigger '{trigger.name}' executed auto_assign: "
+                            f"strategy={result.get('strategy')}, assignee={result.get('new_assignee_id')}"
+                        )
+
+                # Try to execute via ActionExecutor for extensibility
+                else:
+                    result = ActionExecutor.execute_action(db, task, action, context)
+                    if result:
+                        executed_actions.append(result)
+
+            # All actions succeeded, commit the savepoint
+            savepoint.commit()
             status = "success"
-        except Exception as e:
+        except ActionExecutionError as e:
+            # Rollback all changes made by previously executed actions
+            savepoint.rollback()
             status = "failed"
             error_message = str(e)
             executed_actions.append({"type": "error", "message": str(e)})
+            logger.error(f"Trigger '{trigger.name}' action execution failed, rolling back: {e}")
+        except Exception as e:
+            # Rollback all changes made by previously executed actions
+            savepoint.rollback()
+            status = "failed"
+            error_message = str(e)
+            executed_actions.append({"type": "error", "message": str(e)})
+            logger.exception(f"Trigger '{trigger.name}' unexpected error, rolling back: {e}")
 
         log = TriggerLog(
             id=str(uuid.uuid4()),
@@ -198,3 +261,36 @@ class TriggerService:
         )
         db.add(log)
         return log
+
+    @staticmethod
+    def validate_actions(actions: List[Dict[str, Any]], db: Session) -> None:
+        """Validate trigger actions configuration.
+
+        Args:
+            actions: List of action configurations
+            db: Database session
+
+        Raises:
+            ActionValidationError: If any action is invalid
+        """
+        valid_action_types = ["notify", "update_field", "auto_assign"]
+
+        for action in actions:
+            action_type = action.get("type")
+            if not action_type:
+                raise ActionValidationError("Missing action 'type'")
+
+            if action_type not in valid_action_types:
+                raise ActionValidationError(
+                    f"Invalid action type '{action_type}'. "
+                    f"Valid types: {valid_action_types}"
+                )
+
+            # Validate via ActionExecutor for extensible actions
+            if action_type in ["update_field", "auto_assign"]:
+                ActionExecutor.validate_action(action, db)
+
+    @staticmethod
+    def get_supported_action_types() -> List[str]:
+        """Get list of all supported action types."""
+        return ["notify"] + ActionExecutor.get_supported_actions()