feat(server): 设置持久化新增 LLM 模型表与主题字段

- SettingsLlmForm 新增 models 列表（SettingsModelRow：slot/provider/url/apiKey/modelId/type），支持多模型行持久化
- settings 服务读写模型表与主题相关字段，更新 test_settings_persistence 测试

server/tests/test_settings_persistence.py

@@ -146,8 +146,48 @@ def test_runtime_model_config_returns_decrypted_main_model(monkeypatch) -> None:
         assert runtime_model["endpoint"] == "https://api.minimaxi.com/v1"
         assert runtime_model["apiKey"] == "shared-main-key"
         assert runtime_model["capability"] == "chat"
-
-
+
+
+def test_settings_service_persists_additional_model_rows(monkeypatch) -> None:
+    temp_dir = build_temp_secret_dir()
+    monkeypatch.setattr(secret_box, "SECRET_KEY_FILE", temp_dir / "settings.key")
+    monkeypatch.setattr(Base.metadata, "create_all", lambda *args, **kwargs: None)
+    monkeypatch.setenv("HERMES_HOME", str(temp_dir / ".hermes"))
+
+    with build_session(temp_dir / "settings.db") as db:
+        service = SettingsService(db)
+        payload = service.get_settings_snapshot().model_dump()
+        payload["llmForm"]["models"].append(
+            {
+                "slot": "llm_expense_audit",
+                "provider": "MiniMax",
+                "url": "https://api.minimaxi.com/v1",
+                "apiKey": "extra-secret",
+                "apiKeyConfigured": False,
+                "modelId": "MiniMax-Text-01",
+                "type": "llm",
+            }
+        )
+
+        saved_snapshot = service.save_settings_snapshot(SettingsWrite(**payload))
+
+        saved_model = next(
+            model for model in saved_snapshot.llmForm.models if model.slot == "llm_expense_audit"
+        )
+        assert saved_model.provider == "MiniMax"
+        assert saved_model.url == "https://api.minimaxi.com/v1"
+        assert saved_model.modelId == "MiniMax-Text-01"
+        assert saved_model.type == "llm"
+        assert saved_model.apiKey == ""
+        assert saved_model.apiKeyConfigured is True
+
+        model_row = db.get(SystemModelSetting, "llm_expense_audit")
+        assert model_row is not None
+        assert model_row.capability == "chat"
+        assert model_row.priority == 50
+        assert service.load_saved_model_api_key("llm_expense_audit") == "extra-secret"
+
+
 def test_legacy_setup_admin_password_is_migrated_to_database(monkeypatch) -> None:
     temp_dir = build_temp_secret_dir()
     admin_file = temp_dir / "admin.json"