feat(tagged-tasks): Complete core tag management system implementation

- Implements comprehensive tagged task lists system for multi-context task management including core tag management functions (Task 103.11), MCP integration updates, and foundational infrastructure for tagged task operations. Features tag CRUD operations, validation, metadata tracking, deep task copying, and full backward compatibility.

mcp-server/src/tools/add-task.js

@@ -99,7 +99,13 @@ export function registerAddTaskTool(server) {
 					{ session }
 				);
 
-				return handleApiResult(result, log);
+				return handleApiResult(
+					result,
+					log,
+					'Error adding task',
+					undefined,
+					args.projectRoot
+				);
 			} catch (error) {
 				log.error(`Error in add-task tool: ${error.message}`);
 				return createErrorResponse(error.message);