feat(02-02): implement ESP32Transport UDP client with asyncio DatagramProtocol

- ESP32Transport.send_command() injects v:1, fire-and-forget, silent drop if not ready
- 512-byte payload limit enforced with warning log
- datagram_received() parses STATUS ok → connected=True, stores last_status
- on_status callback support for status update notifications
- connection_lost() sets connected=False, clears transport ref
- create_esp32_transport() async factory sends initial STATUS ping (D-12)
- All protocol behaviors match docs/protocol.md exactly (D-10, D-11, D-12, D-14)
- Add pytest-asyncio to dev deps + asyncio_mode=auto for test suite

.gitignore

@@ -0,0 +1,33 @@
+# Python
+__pycache__/
+*.py[cod]
+*.pyo
+*.pyd
+.Python
+*.egg-info/
+dist/
+build/
+*.egg
+
+# Virtual environments
+.venv/
+venv/
+env/
+
+# uv
+.python-version
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Test artifacts
+.pytest_cache/
+.coverage
+htmlcov/