build: 添加 x86 和 arm64 双架构部署包

- 构建 x86 (linux/amd64) backend 和 frontend 镜像
- 导出 arm64 和 x86 两种架构的 tar.gz 镜像包
- 添加 docker-compose.x86.yml 和 docker-compose.arm64.yml
- install.sh 自动检测架构并加载对应镜像
- 部署包约 200MB (backend 75M x2 + frontend 24M x2 + postgres 106M)

deploy/docker-compose.arm64.yml

@@ -0,0 +1,37 @@
+services:
+  db:
+    image: postgres:15-alpine
+    environment:
+      POSTGRES_DB: debt_manager
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    ports:
+      - "54326:5432"
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+  backend:
+    image: debt-manager-backend:latest
+    ports:
+      - "8000:8000"
+    environment:
+      DATABASE_URL: postgresql+asyncpg://postgres:postgres@db:5432/debt_manager
+      SECRET_KEY: change-this-in-production-please
+    depends_on:
+      db:
+        condition: service_healthy
+
+  frontend:
+    image: debt-manager-frontend:latest
+    ports:
+      - "806:80"
+    depends_on:
+      - backend
+
+volumes:
+  pgdata: