feat: 报销预审会话状态管理与工作台交互增强

- 新增差旅报销会话状态管理与对话模型重构
- 增强风险观测服务与运行时聊天上下文作用域
- 优化工作台图标资源、助理意图识别与摘要工具
- 完善报销创建视图样式与差旅详情页标准调整交互
- 补充风险观测、运行时聊天与报销端点测试覆盖

server/tests/test_risk_observations_service.py

@@ -4,6 +4,7 @@ from collections.abc import Generator
 from datetime import UTC, datetime
 from decimal import Decimal
 
+import pytest
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
 from sqlalchemy import create_engine
@@ -124,6 +125,27 @@ def test_platform_rule_flags_are_persisted_as_risk_observations() -> None:
         assert persisted.contribution_scores_json == {"S_rule": 100}
 
 
+def test_risk_observation_storage_ready_is_cached_per_bind(monkeypatch: pytest.MonkeyPatch) -> None:
+    with _build_session() as db:
+        RiskObservationService._storage_ready_cache.clear()
+        create_all_calls = []
+        original_create_all = Base.metadata.create_all
+
+        def spy_create_all(*args, **kwargs):
+            create_all_calls.append(kwargs.get("bind"))
+            return original_create_all(*args, **kwargs)
+
+        monkeypatch.setattr(Base.metadata, "create_all", spy_create_all)
+
+        service = RiskObservationService(db)
+        service.ensure_storage_ready()
+        service.ensure_storage_ready()
+        RiskObservationService(db).ensure_storage_ready()
+
+        assert len(create_all_calls) == 1
+        RiskObservationService._storage_ready_cache.clear()
+
+
 def test_risk_observation_endpoints_return_list_detail_dashboard_and_feedback() -> None:
     client, session_factory = _build_client()
     with session_factory() as db: