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/crm.py

@@ -0,0 +1,57 @@
+"""
+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 datetime import datetime
+from typing import List, Optional
+
+from pydantic import BaseModel, ConfigDict
+
+
+class CrmConnectionOut(BaseModel):
+    """A connected CRM as shown on the integrations page. Never exposes
+    credentials — only identity and health."""
+    model_config = ConfigDict(from_attributes=True)
+
+    provider: str
+    status: str
+    display_name: Optional[str] = None
+    external_account_id: str
+    last_error: Optional[str] = None
+    created_at: Optional[datetime] = None
+    recent_failures: int = 0
+
+
+class CrmTestResult(BaseModel):
+    ok: bool
+    account_name: Optional[str] = None
+    error: Optional[str] = None
+
+
+class CrmCustomerSyncOut(BaseModel):
+    """One CRM link for a person, shown on the People drawer."""
+    model_config = ConfigDict(from_attributes=True)
+
+    provider: str
+    contact_id: Optional[str] = None
+    record_url: Optional[str] = None
+    synced_at: Optional[datetime] = None
+
+
+class PersonCrmStatus(BaseModel):
+    """CRM state for a person: which CRMs the org has connected, and where this
+    person is already synced."""
+    connected_providers: List[str]
+    synced: List[CrmCustomerSyncOut]