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>

deploy/cbpoa-api.service

@@ -0,0 +1,17 @@
+[Unit]
+Description=CBPOA FastAPI backend
+After=network.target
+
+[Service]
+Type=simple
+User=root
+WorkingDirectory=/opt/cbpoa/backend
+Environment=PATH=/opt/cbpoa/backend/.venv/bin:/usr/bin
+EnvironmentFile=-/opt/cbpoa/backend/.env
+ExecStart=/opt/cbpoa/backend/.venv/bin/uvicorn main:app --host 127.0.0.1 --port 8000 --workers 1
+Restart=on-failure
+RestartSec=5
+LimitNOFILE=65535
+
+[Install]
+WantedBy=multi-user.target