feat(models): 组织、用户、角色、客户、会话与消息模型

按组织边界定义数据关系，补齐仓储层与通用工具，迁移脚本可重复执行。

backend/app/models/schemas/ai_config.py

@@ -0,0 +1,58 @@
+"""
+Copyright 2024-2026 ReplyPier
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from pydantic import BaseModel, SecretStr
+from typing import Optional, Dict
+from app.models.ai_config import AIModelType
+from uuid import UUID
+
+
+class AIConfigBase(BaseModel):
+    model_type: AIModelType
+    model_name: str
+    settings: Optional[Dict] = {}
+
+
+class AIConfigCreate(AIConfigBase):
+    api_key: SecretStr
+    # Required for OPENAI_COMPATIBLE (a self-hosted or third-party endpoint);
+    # ignored by providers that don't need it.
+    base_url: Optional[str] = None
+
+
+class AIConfigUpdate(BaseModel):
+    model_type: Optional[AIModelType] = None
+    model_name: Optional[str] = None
+    api_key: Optional[SecretStr] = None
+    settings: Optional[Dict] = None
+    base_url: Optional[str] = None
+
+
+class AIConfigResponse(BaseModel):
+    id: int
+    organization_id: UUID
+    model_type: AIModelType
+    model_name: str
+    is_active: bool
+    settings: Dict = {}
+
+    class Config:
+        from_attributes = True
+
+
+class AISetupResponse(BaseModel):
+    message: str
+    config: AIConfigResponse