feat(handoff): 转人工状态、待接管列表与接待时段

同会话内 AI 转人工，待接管列表按分组和在线状态展示，接管后保留上下文。

backend/tests/services/test_agent_rooms.py

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+"""
+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 types import SimpleNamespace
+from uuid import uuid4
+
+import pytest
+
+from app.models.permission import Permission
+from app.services.agent_rooms import may_join_org_inbox
+
+
+@pytest.fixture
+def viewer(db, test_user, test_role):
+    permission = Permission(name="view_unassigned_chats")
+    db.add(permission)
+    test_role.permissions = [*test_role.permissions, permission]
+    db.commit()
+    return test_user
+
+
+def _socket(user, org=None):
+    return {"user_id": str(user.id), "organization_id": str(org or user.organization_id)}
+
+
+def test_a_viewer_of_unowned_chats_may_join_their_orgs_room(db, viewer):
+    assert may_join_org_inbox(db, _socket(viewer), f"org_inbox_{viewer.organization_id}")
+
+
+def test_not_another_orgs_room(db, viewer):
+    assert not may_join_org_inbox(db, _socket(viewer), f"org_inbox_{uuid4()}")
+
+
+def test_not_without_the_permission(db, test_user):
+    assert not may_join_org_inbox(db, _socket(test_user), f"org_inbox_{test_user.organization_id}")
+
+
+def test_not_once_deactivated_or_deleted(db, viewer):
+    viewer.is_active = False
+    db.commit()
+    assert not may_join_org_inbox(db, _socket(viewer), f"org_inbox_{viewer.organization_id}")
+    ghost = SimpleNamespace(id=uuid4(), organization_id=viewer.organization_id)
+    assert not may_join_org_inbox(db, _socket(ghost), f"org_inbox_{viewer.organization_id}")