Fix all failing tests and pytest collection warnings

Fixed MagicMock comparison errors across multiple test suites by:
- Adding proper ModelCapabilities mocks with real values instead of MagicMock objects
- Updating test_auto_mode.py with correct provider mocking for model availability tests
- Updating test_thinking_modes.py with proper capabilities mocking in all thinking mode tests
- Updating test_tools.py with proper capabilities mocking for CodeReview and Analyze tools
- Fixing test_large_prompt_handling.py by adding proper provider mocking to prevent errors before large prompt detection

Fixed pytest collection warnings by:
- Renaming TestGenRequest to TestGenerationRequest to avoid pytest collecting it as a test class
- Renaming TestGenTool to TestGenerationTool to avoid pytest collecting it as a test class
- Updated all imports and references across server.py, tools/__init__.py, and test files

All 459 tests now pass without warnings or MagicMock comparison errors.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

utils/file_utils.py

@@ -980,7 +980,7 @@ def check_total_file_size(files: list[str], model_name: Optional[str] = None) ->
         model_name: Model name for context-aware thresholds, or None for default
 
     Returns:
-        Dict with MCP_CODE_TOO_LARGE response if too large, None if acceptable
+        Dict with `code_too_large` response if too large, None if acceptable
     """
     if not files:
         return None