feat: 从 SQLite 切换到 PostgreSQL

- Prisma provider 改为 postgresql
- docker-compose 新增 postgres 服务（带健康检查）
- Dockerfile 移除 sqlite3/template.db，改用 npm install prisma 做运行时 schema 同步
- docker-entrypoint.sh 简化为 prisma db push + node server.js

docker-compose.yml

@@ -1,18 +1,42 @@
 services:
+  postgres:
+    image: postgres:16-alpine
+    container_name: no-whatever-db
+    ports:
+      - "5432:5432"
+    environment:
+      POSTGRES_USER: nowhatever
+      POSTGRES_PASSWORD: nowhatever
+      POSTGRES_DB: nowhatever
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U nowhatever"]
+      interval: 5s
+      timeout: 3s
+      retries: 5
+    restart: unless-stopped
+    networks:
+      - nginx
+
   app:
     build: .
     image: no-whatever:latest
     container_name: no-whatever
     ports:
       - "3000:3000"
-    volumes:
-      - /data/no-whatever:/app/data
     environment:
-      - DATABASE_URL=file:/app/data/prod.db
+      - DATABASE_URL=postgresql://nowhatever:nowhatever@postgres:5432/nowhatever
+    depends_on:
+      postgres:
+        condition: service_healthy
     restart: unless-stopped
     networks:
       - nginx
 
+volumes:
+  pgdata:
+
 networks:
   nginx:
     external: true