fix(firstleg): expose container documents and aggregate departure gates

firstleg/src/main/resources/openapi/firstleg-v1.yaml

@@ -356,6 +356,16 @@ paths:
         required: true
         content: {application/json: {schema: {$ref: '#/components/schemas/ContainerDocumentAttachRequest'}}}
       responses: {'200': {description: 成功、文件归属不匹配或版本冲突}}
+  /api/platform/v1/containers/{id}/clearance/document/{fileId}/download:
+    get:
+      summary: 下载货柜目的港清关附件
+      description: 需要 platform:firstleg:customs:manage 权限；服务端校验当前 DESTINATION_CLEARANCE fileId 及 File 业务归属，完成态仍可下载，响应禁止缓存
+      parameters:
+        - {$ref: '#/components/parameters/ContainerBookingId'}
+        - {name: fileId, in: path, required: true, schema: {type: string, pattern: '^[1-9][0-9]*$'}}
+      responses:
+        '200': {description: 附件二进制内容，包含 Content-Disposition 与 Cache-Control no-store}
+        '404': {description: 当前附件不存在或归属不匹配}
   /api/platform/v1/containers/{id}/clearance/document/upload:
     post:
       summary: 直接选择文件上传或替换货柜目的港清关资料