feat: Enhance testing, CLI flag validation, and AI capabilities

This commit introduces several significant improvements:

- **Enhanced Unit Testing:**  Vastly improved unit tests for the  module, covering core functions, edge cases, and error handling.  Simplified test functions and comprehensive mocking were implemented for better isolation and reliability. Added new section to tests.mdc detailing reliable testing techniques.

- **CLI Kebab-Case Flag Enforcement:**  The CLI now enforces kebab-case for flags, providing helpful error messages when camelCase is used. This improves consistency and user experience.

- **AI Enhancements:**
    - Enabled 128k token output for Claude 3.7 Sonnet by adding the  header.
    - Added a new task to  to document this change and its testing strategy.
    - Added unit tests to verify the Anthropic client configuration.
    - Added  and  utility functions.

- **Improved Test Coverage:** Added tests for the new CLI flag validation logic.

.cursor/rules/tests.mdc

@@ -433,6 +433,111 @@ npm test -- -t "pattern to match"
   - Reset state in `beforeEach` and `afterEach` hooks
   - Avoid global state modifications
 
+## Reliable Testing Techniques
+
+- **Create Simplified Test Functions**
+  - Create simplified versions of complex functions that focus only on core logic
+  - Remove file system operations, API calls, and other external dependencies
+  - Pass all dependencies as parameters to make testing easier
+  
+  ```javascript
+  // Original function (hard to test)
+  const setTaskStatus = async (taskId, newStatus) => {
+    const tasksPath = 'tasks/tasks.json';
+    const data = await readJSON(tasksPath);
+    // Update task status logic
+    await writeJSON(tasksPath, data);
+    return data;
+  };
+  
+  // Test-friendly simplified function (easy to test)
+  const testSetTaskStatus = (tasksData, taskIdInput, newStatus) => {
+    // Same core logic without file operations
+    // Update task status logic on provided tasksData object
+    return tasksData; // Return updated data for assertions
+  };
+  ```
+
+- **Avoid Real File System Operations**
+  - Never write to real files during tests
+  - Create test-specific versions of file operation functions
+  - Mock all file system operations including read, write, exists, etc.
+  - Verify function behavior using the in-memory data structures
+  
+  ```javascript
+  // Mock file operations
+  const mockReadJSON = jest.fn();
+  const mockWriteJSON = jest.fn();
+  
+  jest.mock('../../scripts/modules/utils.js', () => ({
+    readJSON: mockReadJSON,
+    writeJSON: mockWriteJSON,
+  }));
+  
+  test('should update task status correctly', () => {
+    // Setup mock data
+    const testData = JSON.parse(JSON.stringify(sampleTasks));
+    mockReadJSON.mockReturnValue(testData);
+    
+    // Call the function that would normally modify files
+    const result = testSetTaskStatus(testData, '1', 'done');
+    
+    // Assert on the in-memory data structure
+    expect(result.tasks[0].status).toBe('done');
+  });
+  ```
+
+- **Data Isolation Between Tests**
+  - Always create fresh copies of test data for each test
+  - Use `JSON.parse(JSON.stringify(original))` for deep cloning
+  - Reset all mocks before each test with `jest.clearAllMocks()`
+  - Avoid state that persists between tests
+  
+  ```javascript
+  beforeEach(() => {
+    jest.clearAllMocks();
+    // Deep clone the test data
+    testTasksData = JSON.parse(JSON.stringify(sampleTasks));
+  });
+  ```
+
+- **Test All Path Variations**
+  - Regular tasks and subtasks
+  - Single items and multiple items
+  - Success paths and error paths
+  - Edge cases (empty data, invalid inputs, etc.)
+  
+  ```javascript
+  // Multiple test cases covering different scenarios
+  test('should update regular task status', () => {
+    /* test implementation */
+  });
+  
+  test('should update subtask status', () => {
+    /* test implementation */
+  });
+  
+  test('should update multiple tasks when given comma-separated IDs', () => {
+    /* test implementation */
+  });
+  
+  test('should throw error for non-existent task ID', () => {
+    /* test implementation */
+  });
+  ```
+
+- **Stabilize Tests With Predictable Input/Output**
+  - Use consistent, predictable test fixtures
+  - Avoid random values or time-dependent data
+  - Make tests deterministic for reliable CI/CD
+  - Control all variables that might affect test outcomes
+  
+  ```javascript
+  // Use a specific known date instead of current date
+  const fixedDate = new Date('2023-01-01T12:00:00Z');
+  jest.spyOn(global, 'Date').mockImplementation(() => fixedDate);
+  ```
+
 See [tests/README.md](mdc:tests/README.md) for more details on the testing approach.
 
 Refer to [jest.config.js](mdc:jest.config.js) for Jest configuration options.