feat(cache): Implement caching for listTasks MCP endpoint

Implemented LRU caching for the  function to improve performance for repeated requests.

Key changes include:
- Added  dependency.
- Introduced a reusable  utility function in  leveraging a .
- Refactored  in  to use the caching utility with a key based on task path, filter, and subtask flag.
- Modified  to include the  boolean flag in the final JSON response structure, nesting the original data under a  key.
- Added  function and corresponding MCP tool () for monitoring cache performance.
- Improved error handling in  for cases where  is not found.

This addresses the previous issue of the empty task list likely caused by stale cache entries and provides clear visibility into whether a response is served from the cache.

Relates to #23.9

tests/integration/mcp-server/direct-functions.test.js

@@ -24,8 +24,8 @@ const mockLogger = {
 };
 
 // Test file paths
-const testProjectRoot = path.join(__dirname, '../../fixtures/test-project');
-const testTasksPath = path.join(testProjectRoot, 'tasks.json');
+const testProjectRoot = path.join(__dirname, '../../fixture');
+const testTasksPath = path.join(testProjectRoot, 'test-tasks.json');
 
 describe('MCP Server Direct Functions', () => {
   // Create test data before tests