cleanup: remove Windows native support, enforce WSL requirement

Remove Windows batch scripts and native setup instructions since Claude Code CLI
requires WSL on Windows. Consolidate Docker as primary recommendation across all platforms.

Changes:
- Remove setup.bat, run_gemini.bat, setup-docker-env.bat
- Remove examples/claude_config_windows.json
- Update README to clarify WSL requirement for Windows users
- Promote Docker as recommended setup for all platforms
- Update troubleshooting section for WSL-only support
- Apply code formatting fixes from ruff/black

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

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

server.py

@@ -81,7 +81,7 @@ def configure_gemini():
     """
     api_key = os.getenv("GEMINI_API_KEY")
     if not api_key:
-        raise ValueError("GEMINI_API_KEY environment variable is required. " "Please set it with your Gemini API key.")
+        raise ValueError("GEMINI_API_KEY environment variable is required. Please set it with your Gemini API key.")
     # Note: We don't store the API key globally for security reasons
     # Each tool creates its own Gemini client with the API key when needed
     logger.info("Gemini API key found")