chore: Remove client-specific docs, fix linter errors, update documentation

- Remove SPYKE-related client documentation files
- Fix critical ruff linter errors:
  - Remove unused 'os' import in test_analyze_e2e.py
  - Remove unused 'setups' variable in test_test_example_extractor.py
  - Prefix unused output_dir parameter with underscore in codebase_scraper.py
  - Fix import sorting in test_integration.py
- Update CHANGELOG.md with comprehensive C3.9 and enhancement features
- Update CLAUDE.md with --enhance-level documentation

All critical code quality issues resolved.

tests/test_test_example_extractor.py

@@ -360,9 +360,8 @@ public class GameControllerTests
         instantiations = [e for e in examples if e.category == "instantiation"]
         self.assertGreater(len(instantiations), 0)
 
-        # Check for setup extraction
-        setups = [e for e in examples if e.category == "setup"]
-        # May or may not have setups depending on extraction
+        # Setup extraction may or may not occur depending on test patterns
+        # No assertion needed as setup examples are optional
 
     def test_extract_csharp_with_mocks(self):
         """Test C# mock pattern extraction (NSubstitute)"""