Add map-frontend (nginx + MapLibre GL), make pmtiles internal-only

- map-frontend: nginx serves MapLibre GL static app, proxies /tiles/ to pmtiles internally
- pmtiles: remove host port binding (internal to npm-network only), update public-url
- 5 themes: light, dark, grayscale, white, black

map-frontend/docker-compose.yaml

@@ -0,0 +1,16 @@
+services:
+  map-frontend:
+    image: nginx:alpine
+    container_name: map-frontend
+    restart: unless-stopped
+    ports:
+      - "8087:80"
+    volumes:
+      - ./nginx.conf:/etc/nginx/conf.d/default.conf:ro
+      - ./html:/usr/share/nginx/html:ro
+    networks:
+      - npm-network
+
+networks:
+  npm-network:
+    external: true