refactor: 移除 Python 后端源码，全面迁移至 Rust gateway 架构

- 删除全部 Python 源码 (src/) 及 Alembic 迁移脚本，归档至 _deprecated_py_src/
- 重构 Rust gateway ai_pipeline: 拆分 planner/finalize 模块，新增 contracts/adaptation 层
- 重组 handlers 模块为 admin/public/proxy/internal/shared 子模块结构
- 新增 executor 模块，引入 Rust 原生数据库迁移 (aether-data/migrations)
- 简化 CI/Docker 构建流程，移除 base image 二级构建，统一为单一 app image
- 移除 Python 相关基础设施文件 (entrypoint.sh, gunicorn_conf.py, Dockerfile.base)

_deprecated_py_src/services/user/preference.py

@@ -0,0 +1,139 @@
+"""
+用户偏好设置服务
+"""
+
+from __future__ import annotations
+
+from sqlalchemy.orm import Session
+
+from src.core.exceptions import NotFoundException
+from src.core.logger import logger
+from src.models.database import Provider, User, UserPreference
+from src.services.wallet import WalletService
+
+
+class PreferenceService:
+    """用户偏好设置服务"""
+
+    @staticmethod
+    def get_or_create_preferences(db: Session, user_id: str) -> UserPreference:  # UUID
+        """获取或创建用户偏好设置"""
+        preferences = db.query(UserPreference).filter(UserPreference.user_id == user_id).first()
+
+        if not preferences:
+            # 创建默认偏好设置
+            preferences = UserPreference(
+                user_id=user_id,
+                theme="light",
+                language="zh-CN",
+                timezone="Asia/Shanghai",
+                email_notifications=True,
+                usage_alerts=True,
+                announcement_notifications=True,
+            )
+            db.add(preferences)
+            db.commit()
+            db.refresh(preferences)
+            logger.info(f"Created default preferences for user {user_id}")
+
+        return preferences
+
+    @staticmethod
+    def update_preferences(
+        db: Session,
+        user_id: str,  # UUID
+        avatar_url: str | None = None,
+        bio: str | None = None,
+        default_provider_id: str | None = None,  # UUID
+        theme: str | None = None,
+        language: str | None = None,
+        timezone: str | None = None,
+        email_notifications: bool | None = None,
+        usage_alerts: bool | None = None,
+        announcement_notifications: bool | None = None,
+    ) -> UserPreference:
+        """更新用户偏好设置"""
+        preferences = PreferenceService.get_or_create_preferences(db, user_id)
+
+        # 更新提供的字段
+        if avatar_url is not None:
+            preferences.avatar_url = avatar_url
+        if bio is not None:
+            preferences.bio = bio
+        if default_provider_id is not None:
+            # 验证提供商是否存在且活跃
+            provider = (
+                db.query(Provider)
+                .filter(Provider.id == default_provider_id, Provider.is_active == True)
+                .first()
+            )
+            if not provider:
+                raise NotFoundException("Provider not found or inactive")
+            preferences.default_provider_id = default_provider_id
+        if theme is not None:
+            if theme not in ["light", "dark", "auto", "system"]:
+                raise ValueError("Invalid theme. Must be 'light', 'dark', 'auto', or 'system'")
+            preferences.theme = theme
+        if language is not None:
+            preferences.language = language
+        if timezone is not None:
+            preferences.timezone = timezone
+        if email_notifications is not None:
+            preferences.email_notifications = email_notifications
+        if usage_alerts is not None:
+            preferences.usage_alerts = usage_alerts
+        if announcement_notifications is not None:
+            preferences.announcement_notifications = announcement_notifications
+
+        db.commit()
+        db.refresh(preferences)
+        logger.info(f"Updated preferences for user {user_id}")
+
+        return preferences
+
+    @staticmethod
+    def get_user_with_preferences(db: Session, user_id: str) -> dict:  # UUID
+        """获取用户信息及其偏好设置"""
+        user = db.query(User).filter(User.id == user_id).first()
+        if not user:
+            raise NotFoundException("User not found")
+
+        preferences = PreferenceService.get_or_create_preferences(db, user_id)
+        wallet = WalletService.get_wallet(db, user_id=user.id)
+        billing = WalletService.serialize_wallet_summary(wallet)
+
+        # 构建返回数据
+        user_data = {
+            "id": user.id,
+            "email": user.email,
+            "username": user.username,
+            "role": user.role.value,
+            "is_active": user.is_active,
+            "created_at": user.created_at,
+            "last_login_at": user.last_login_at,
+            "auth_source": user.auth_source.value if user.auth_source else "local",
+            "has_password": bool(user.password_hash),
+            "preferences": {
+                "avatar_url": preferences.avatar_url,
+                "bio": preferences.bio,
+                "default_provider": (
+                    preferences.default_provider.name if preferences.default_provider else None
+                ),
+                "theme": preferences.theme,
+                "language": preferences.language,
+                "timezone": preferences.timezone,
+                "notifications": {
+                    "email": preferences.email_notifications,
+                    "usage_alerts": preferences.usage_alerts,
+                    "announcements": preferences.announcement_notifications,
+                },
+            },
+            "billing": billing,
+            "stats": {
+                "total_cost": billing["total_consumed"],
+                "total_cost_all_time": billing["total_consumed"],
+                "api_keys_count": len(user.api_keys),
+            },
+        }
+
+        return user_data