feat: GeoScene frontend POC + Docker deploy for remote host

Migrate maps to @geoscene/core, polish monitoring/alerts UX, fix timeline
basemap flicker and district alert regions, and ship compose/nginx Docker
deploy assets with CBPOA_ROOT data mounts.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/utils/district_lookup.py

@@ -0,0 +1,21 @@
+"""Map 100m grid_id (r{row}_c{col}) → Wuhan district name."""
+from functools import lru_cache
+
+import pandas as pd
+
+from config import PROJECT_ROOT
+
+
+@lru_cache(maxsize=1)
+def grid_district_lookup() -> dict[str, str]:
+    """Loaded once from processed/grid_district_mapping.parquet."""
+    path = PROJECT_ROOT / "processed" / "grid_district_mapping.parquet"
+    if not path.exists():
+        return {}
+    df = pd.read_parquet(path)
+    df = df.dropna(subset=["district_name"])
+    return dict(zip(df["grid_id"].astype(str), df["district_name"].astype(str)))
+
+
+def district_for_grid(grid_id: str, default: str = "其他") -> str:
+    return grid_district_lookup().get(grid_id, default)