feat: Sidecar V2 — multi-pool provider proxy with 429 cooldown

- proxy.py: Fix route path duplication (v1/v1 → v1) when upstream
  base URL already includes /v1 prefix
- proxy.py: Fix _emergency_count global variable for metrics tracking
- server.py: Add logging.basicConfig(level=logging.INFO) for structlog
  INFO-level log visibility
- Full multi-pool routing: primary → fallback → emergency passthrough
- Per-backend rate limiting with RPM-based token bucket
- 429 cooldown mechanism with automatic recovery
- Dashboard with SSE real-time monitoring
- Admin API for backend/pool/config management
- SQLite-backed persistence with encrypted API key storage
- Docker compose deployment

Deployed by opengineer 严维序 as BIZ-50 Step 4

deploy/sidecar-v2.service

@@ -0,0 +1,23 @@
+[Unit]
+Description=Sidecar V2 — Multi-Pool Provider Proxy
+After=network.target
+
+[Service]
+Type=simple
+User=openclaw
+Group=openclaw
+WorkingDirectory=/opt/sidecar-v2
+EnvironmentFile=/etc/sidecar-v2/env
+ExecStart=/opt/sidecar-v2/.venv/bin/python3 main.py
+Restart=always
+RestartSec=5
+
+# Security hardening
+NoNewPrivileges=yes
+ProtectSystem=strict
+ProtectHome=yes
+ReadWritePaths=/opt/sidecar-v2/data
+PrivateTmp=yes
+
+[Install]
+WantedBy=multi-user.target