Refactor Docker setup and enhance development environment

- Updated docker-compose.dev.yml to use Dockerfile.dev for backend builds and added HOST environment variable for frontend.
- Introduced Dockerfile.dev for streamlined backend development with Go.
- Enhanced development documentation to reflect changes in local setup and API proxying.
- Removed outdated frontend Dockerfile and adjusted frontend configuration for improved development experience.

docker-compose.dev.yml

@@ -1,30 +1,31 @@
-# Development: backend (Go) on 8080, frontend (Nuxt dev) on 3000 with proxy to backend.
-# Open http://localhost:3000/map/ — /map/api, /map/updates, /map/grids are proxied to backend.
-
-services:
-  backend:
-    build:
-      context: .
-      dockerfile: Dockerfile
-    ports:
-      - "3080:3080"
-    volumes:
-      - ./grids:/map
-    environment:
-      - HNHMAP_PORT=3080
-      - HNHMAP_BOOTSTRAP_PASSWORD=admin
-
-  frontend:
-    image: node:20-alpine
-    working_dir: /app
-    command: sh -c "npm ci && npm run dev"
-    ports:
-      - "3000:3000"
-    volumes:
-      - ./frontend-nuxt:/app
-      # Prevent overwriting node_modules from host
-      - /app/node_modules
-    environment:
-      - NUXT_PUBLIC_API_BASE=/map/api
-    depends_on:
-      - backend
+# Development: backend API on 3080 + frontend Nuxt dev server on 3000.
+# Open http://localhost:3000/ for app development with live-reload.
+
+services:
+  backend:
+    build:
+      context: .
+      dockerfile: Dockerfile.dev
+    ports:
+      - "3080:3080"
+    volumes:
+      - ./grids:/map
+    environment:
+      - HNHMAP_PORT=3080
+      - HNHMAP_BOOTSTRAP_PASSWORD=admin
+
+  frontend:
+    image: node:20-alpine
+    working_dir: /app
+    command: sh -c "npm ci && npm run dev"
+    ports:
+      - "3000:3000"
+    volumes:
+      - ./frontend-nuxt:/app
+      # Prevent overwriting node_modules from host
+      - /app/node_modules
+    environment:
+      - NUXT_PUBLIC_API_BASE=/map/api
+      - HOST=0.0.0.0
+    depends_on:
+      - backend