Add batch management APIs, API security, rate limiting, and optimizations

- Batch device CRUD: POST /api/devices/batch (create 500), PUT /api/devices/batch (update 500),
  POST /api/devices/batch-delete (delete 100) with WHERE IN bulk queries
- Batch command: POST /api/commands/batch with model_validator mutual exclusion
- API key auth (X-API-Key header, secrets.compare_digest timing-safe)
- Rate limiting via SlowAPIMiddleware (60/min default, 30/min writes)
- Real client IP extraction (X-Forwarded-For / CF-Connecting-IP)
- Global exception handler (no stack trace leaks, passes HTTPException through)
- CORS with auto-disable credentials on wildcard origins
- Schema validation: IMEI pattern, lat/lon ranges, Literal enums, MAC/UUID patterns
- Heartbeats router, per-ID endpoints for locations/attendance/bluetooth
- Input dedup in batch create, result ordering preserved
- Baidu reverse geocoding, Gaode map tiles with WGS84→GCJ02 conversion
- Device detail panel with feature toggles and command controls
- Side panel for location/beacon pages with auto-select active device

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>

app/extensions.py

@@ -0,0 +1,22 @@
+"""
+Shared extension instances (rate limiter, etc.) to avoid circular imports.
+"""
+
+from starlette.requests import Request
+from slowapi import Limiter
+
+from app.config import settings
+
+
+def _get_real_client_ip(request: Request) -> str:
+    """Extract real client IP from X-Forwarded-For (behind Cloudflare/nginx) or fallback."""
+    forwarded = request.headers.get("X-Forwarded-For")
+    if forwarded:
+        return forwarded.split(",")[0].strip()
+    cf_ip = request.headers.get("CF-Connecting-IP")
+    if cf_ip:
+        return cf_ip.strip()
+    return request.client.host if request.client else "127.0.0.1"
+
+
+limiter = Limiter(key_func=_get_real_client_ip, default_limits=[settings.RATE_LIMIT_DEFAULT])