Initial commit: S10 remote control module, demos, and docs

- s10_robot.py: protocol framing, mTLS client, heartbeat, status and control APIs
- demo_stand_rotate_lie.py: stand, rotate in place, lie down with safe recovery
- status_probe.py: read-only status subscription
- tests: protocol unit tests and local fake robot
- docs: remote control command reference

.gitignore

@@ -0,0 +1,15 @@
+# Python
+.venv/
+__pycache__/
+*.py[cod]
+*.egg-info/
+
+# 证书与私钥（不入库）
+certs/
+*.key
+*.crt
+*.pem
+
+# 日志与临时文件
+*.log
+.DS_Store