feat (infra): Trae 完成 asset_helper_backend 微服务基础架构 V1 初始化

核心实现：搭建 Monorepo 架构，完成 shared 共享包、gateway、user-service 基础框架开发
技术落地：严格匹配指定技术栈版本，完成 Docker、gRPC、FastAPI、PostgreSQL、Redis 等配置，实现服务间基础连通
配套文件：生成 Makefile、环境变量模板、数据库 / 脚本初始化文件及启动验证文档
架构定位：仅搭建基础架构骨架，无任何业务逻辑、业务规则及业务相关字段，为后续业务开发提供支撑

asset_helper_backend/services/user-service/app/api/user_service.py

@@ -0,0 +1,112 @@
+import grpc
+from concurrent import futures
+from app.grpc_generated import user_pb2, user_pb2_grpc
+from app.db.models import User
+from app.db.session import AsyncSessionLocal
+from sqlalchemy import select
+from datetime import datetime
+
+class UserService(user_pb2_grpc.UserServiceServicer):
+    async def GetUser(self, request, context):
+        async with AsyncSessionLocal() as session:
+            result = await session.execute(select(User).where(User.id == request.id))
+            user = result.scalar_one_or_none()
+            if not user:
+                context.set_code(grpc.StatusCode.NOT_FOUND)
+                context.set_details("User not found")
+                return user_pb2.UserResponse()
+            
+            return user_pb2.UserResponse(
+                user=user_pb2.User(
+                    id=user.id,
+                    username=user.username,
+                    password_hash=user.password_hash,
+                    created_at=user.created_at.isoformat(),
+                    updated_at=user.updated_at.isoformat()
+                )
+            )
+    
+    async def CreateUser(self, request, context):
+        async with AsyncSessionLocal() as session:
+            user = User(
+                username=request.username,
+                password_hash=request.password_hash
+            )
+            session.add(user)
+            await session.commit()
+            await session.refresh(user)
+            
+            return user_pb2.UserResponse(
+                user=user_pb2.User(
+                    id=user.id,
+                    username=user.username,
+                    password_hash=user.password_hash,
+                    created_at=user.created_at.isoformat(),
+                    updated_at=user.updated_at.isoformat()
+                )
+            )
+    
+    async def UpdateUser(self, request, context):
+        async with AsyncSessionLocal() as session:
+            result = await session.execute(select(User).where(User.id == request.id))
+            user = result.scalar_one_or_none()
+            if not user:
+                context.set_code(grpc.StatusCode.NOT_FOUND)
+                context.set_details("User not found")
+                return user_pb2.UserResponse()
+            
+            user.username = request.username
+            user.password_hash = request.password_hash
+            await session.commit()
+            await session.refresh(user)
+            
+            return user_pb2.UserResponse(
+                user=user_pb2.User(
+                    id=user.id,
+                    username=user.username,
+                    password_hash=user.password_hash,
+                    created_at=user.created_at.isoformat(),
+                    updated_at=user.updated_at.isoformat()
+                )
+            )
+    
+    async def DeleteUser(self, request, context):
+        async with AsyncSessionLocal() as session:
+            result = await session.execute(select(User).where(User.id == request.id))
+            user = result.scalar_one_or_none()
+            if not user:
+                context.set_code(grpc.StatusCode.NOT_FOUND)
+                context.set_details("User not found")
+                return user_pb2.EmptyResponse()
+            
+            await session.delete(user)
+            await session.commit()
+            
+            return user_pb2.EmptyResponse()
+    
+    async def ListUsers(self, request, context):
+        async with AsyncSessionLocal() as session:
+            offset = (request.page - 1) * request.page_size
+            result = await session.execute(
+                select(User).offset(offset).limit(request.page_size)
+            )
+            users = result.scalars().all()
+            
+            total_result = await session.execute(select(User))
+            total = len(total_result.scalars().all())
+            
+            user_list = [
+                user_pb2.User(
+                    id=user.id,
+                    username=user.username,
+                    password_hash=user.password_hash,
+                    created_at=user.created_at.isoformat(),
+                    updated_at=user.updated_at.isoformat()
+                )
+                for user in users
+            ]
+            
+            return user_pb2.UsersResponse(
+                users=user_list,
+                total=total
+            )