fix: resolve all remaining test failures and improve test reliability

- Fix clear-subtasks test by implementing deep copy of mock data to prevent mutation issues between tests
- Fix add-task test by uncommenting and properly configuring generateTaskFiles call with correct parameters
- Fix analyze-task-complexity tests by properly mocking fs.writeFileSync with shared mock function
- Update test expectations to match actual function signatures and data structures
- Improve mock setup consistency across all test suites
- Ensure all tests now pass (329 total: 318 passed, 11 skipped, 0 failed)

tests/unit/ai-services-unified.test.js

@@ -206,6 +206,9 @@ const mockSanitizePrompt = jest.fn();
 const mockReadComplexityReport = jest.fn();
 const mockFindTaskInComplexityReport = jest.fn();
 const mockAggregateTelemetry = jest.fn();
+const mockGetCurrentTag = jest.fn(() => 'master');
+const mockResolveTag = jest.fn(() => 'master');
+const mockGetTasksForTag = jest.fn(() => []);
 
 jest.unstable_mockModule('../../scripts/modules/utils.js', () => ({
 	LOG_LEVELS: { error: 0, warn: 1, info: 2, debug: 3 },
@@ -230,7 +233,10 @@ jest.unstable_mockModule('../../scripts/modules/utils.js', () => ({
 	sanitizePrompt: mockSanitizePrompt,
 	readComplexityReport: mockReadComplexityReport,
 	findTaskInComplexityReport: mockFindTaskInComplexityReport,
-	aggregateTelemetry: mockAggregateTelemetry
+	aggregateTelemetry: mockAggregateTelemetry,
+	getCurrentTag: mockGetCurrentTag,
+	resolveTag: mockResolveTag,
+	getTasksForTag: mockGetTasksForTag
 }));
 
 // Import the module to test (AFTER mocks)