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/src/app/api/v1/endpoints/steward.py

@@ -0,0 +1,78 @@
+from __future__ import annotations
+
+import asyncio
+import json
+from collections.abc import AsyncIterator
+from typing import Annotated, Any
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.responses import StreamingResponse
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db
+from app.schemas.common import ErrorResponse
+from app.schemas.steward import StewardPlanRequest, StewardPlanResponse
+from app.services.runtime_chat import RuntimeChatService
+from app.services.steward_intent_agent import StewardIntentAgent
+from app.services.steward_planner import StewardPlannerService
+
+router = APIRouter(prefix="/steward")
+DbSession = Annotated[Session, Depends(get_db)]
+
+
+@router.post(
+    "/plans",
+    response_model=StewardPlanResponse,
+    summary="生成小财管家任务计划",
+    description="把首页自然语言和附件元信息拆解为可确认、可追踪、可分派的财务任务计划。",
+    responses={
+        status.HTTP_400_BAD_REQUEST: {
+            "model": ErrorResponse,
+            "description": "请求缺少任务描述，无法生成小财管家计划。",
+        }
+    },
+)
+def create_steward_plan(payload: StewardPlanRequest, db: DbSession) -> StewardPlanResponse:
+    try:
+        return _build_steward_planner(db).build_plan(payload)
+    except ValueError as exc:
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(exc)) from exc
+
+
+@router.post(
+    "/plans/stream",
+    summary="流式生成小财管家任务计划",
+    description="以 NDJSON 逐条返回小财管家的过程摘要事件，最后返回完整任务计划。",
+)
+async def stream_steward_plan(payload: StewardPlanRequest, db: DbSession) -> StreamingResponse:
+    return StreamingResponse(
+        _iter_steward_plan_events(payload, _build_steward_planner(db)),
+        media_type="application/x-ndjson",
+    )
+
+
+async def _iter_steward_plan_events(
+    payload: StewardPlanRequest,
+    planner: StewardPlannerService,
+) -> AsyncIterator[str]:
+    try:
+        plan = planner.build_plan(payload)
+    except ValueError as exc:
+        yield _encode_stream_event("error", {"message": str(exc)})
+        return
+
+    for event in plan.thinking_events:
+        yield _encode_stream_event("thinking", event.model_dump(mode="json"))
+        await asyncio.sleep(0.18)
+
+    yield _encode_stream_event("plan", plan.model_dump(mode="json"))
+
+
+def _encode_stream_event(event: str, data: dict[str, Any]) -> str:
+    return json.dumps({"event": event, "data": data}, ensure_ascii=False) + "\n"
+
+
+def _build_steward_planner(db: Session) -> StewardPlannerService:
+    return StewardPlannerService(
+        intent_agent=StewardIntentAgent(RuntimeChatService(db)),
+    )