fix: COPY init.sql into DB image, remove Next.js basePath for Traefik prefix stripping

docker-compose.yaml

@@ -37,7 +37,9 @@ services:
 
   # 3. MySQL Database Service
   db:
-    image: mysql:8.0
+    build:
+      context: .
+      dockerfile: ./docker/db/Dockerfile
     container_name: gis_db
     command: --default-authentication-plugin=mysql_native_password
     # No host port mapping - DB is only accessible internally via gis-network
@@ -46,7 +48,6 @@ services:
       - MYSQL_DATABASE=spbu_db
     volumes:
       - db-data:/var/lib/mysql
-      - ./docker/db/init.sql:/docker-entrypoint-initdb.d/init.sql:ro
     networks:
       - gis-network