Add WebSocket, multi API key, geocoding proxy, beacon map picker, and comprehensive bug fixes

- Multi API Key + permission system (read/write/admin) with SHA-256 hash
- WebSocket real-time push (location, alarm, device_status, attendance, bluetooth)
- Geocoding proxy endpoints for Amap POI search and reverse geocode
- Beacon modal map-based location picker with search and click-to-select
- GCJ-02 ↔ WGS-84 bidirectional coordinate conversion
- Data cleanup scheduler (configurable retention days)
- Fix GPS longitude sign inversion (course_status bit 11: 0=East, 1=West)
- Fix 2G CellID 2→3 bytes across all protocols (0x28, 0x2C, parser.py)
- Fix parser loop guards, alarm_source field length, CommandLog.sent_at
- Fix geocoding IMEI parameterization, require_admin import
- Improve API error messages for 422 validation errors
- Remove beacon floor/area fields (consolidated into name)

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

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

app/routers/geocoding.py

@@ -0,0 +1,55 @@
+"""Geocoding proxy endpoints — keeps AMAP_KEY server-side."""
+
+from fastapi import APIRouter, Query
+import httpx
+
+from app.config import settings
+from app.geocoding import reverse_geocode, _amap_sign, AMAP_KEY
+
+router = APIRouter(prefix="/api/geocode", tags=["geocoding"])
+
+
+@router.get("/search")
+async def search_location(
+    keyword: str = Query(..., min_length=1, max_length=100),
+    city: str = Query(default="", max_length=50),
+):
+    """Proxy for Amap POI text search. Returns GCJ-02 coordinates."""
+    if not AMAP_KEY:
+        return {"results": []}
+    params = {
+        "key": AMAP_KEY,
+        "keywords": keyword,
+        "output": "json",
+        "offset": "10",
+        "page": "1",
+    }
+    if city:
+        params["city"] = city
+    sig = _amap_sign(params)
+    if sig:
+        params["sig"] = sig
+    async with httpx.AsyncClient(timeout=5.0) as client:
+        resp = await client.get("https://restapi.amap.com/v3/place/text", params=params)
+        data = resp.json()
+    if data.get("status") != "1":
+        return {"results": []}
+    results = []
+    for poi in data.get("pois", [])[:10]:
+        if poi.get("location"):
+            results.append({
+                "name": poi.get("name", ""),
+                "address": poi.get("address", ""),
+                "location": poi["location"],  # "lng,lat" in GCJ-02
+            })
+    return {"results": results}
+
+
+@router.get("/reverse")
+async def reverse_geocode_endpoint(
+    lat: float = Query(..., ge=-90, le=90),
+    lon: float = Query(..., ge=-180, le=180),
+):
+    """Reverse geocode WGS-84 coords to address via Amap."""
+    address = await reverse_geocode(lat, lon)
+    return {"address": address or ""}