feat: 初始化孕育无忧全栈项目基础代码结构

完成项目初始搭建，包含后端FastAPI+MongoDB服务、前端React+Vite项目的完整基础结构，添加各类配置文件与依赖清单，涵盖核心业务初始框架。

backend/app/routers/chat.py

@@ -0,0 +1,98 @@
+import logging
+from datetime import datetime, timezone
+
+from fastapi import APIRouter, Depends, HTTPException
+
+from app.middleware.auth import get_current_user
+from app.models.chat import ChatSession, ChatMessage
+from app.models.report import Report
+from app.models.user import User
+from app.schemas.chat import ChatMessageRequest, ChatSessionResponse, ChatMessageResponse
+from app.services.ai_service import chat_with_ai
+from app.utils.helpers import parse_object_id
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter()
+
+
+@router.post("/{report_id}/message")
+async def send_message(
+    report_id: str,
+    req: ChatMessageRequest,
+    user: User = Depends(get_current_user),
+):
+    """发送消息并获取 AI 回复"""
+    oid = parse_object_id(report_id)
+    report = await Report.get(oid)
+    if not report or report.user_id != user.id:
+        raise HTTPException(status_code=404, detail="报告不存在")
+
+    # Get or create chat session
+    session = await ChatSession.find_one(
+        ChatSession.user_id == user.id,
+        ChatSession.report_id == report.id,
+    )
+    if not session:
+        session = ChatSession(user_id=user.id, report_id=report.id)
+        await session.insert()
+
+    # Add user message
+    user_msg = ChatMessage(role="user", content=req.content)
+    session.messages.append(user_msg)
+
+    # Get AI response
+    history = [{"role": m.role, "content": m.content} for m in session.messages[:-1]]
+    try:
+        ai_response = await chat_with_ai(report, user, history, req.content)
+    except Exception:
+        logger.exception("AI 对话失败 report_id=%s", report_id)
+        raise HTTPException(status_code=502, detail="AI 对话服务暂时不可用，请稍后重试")
+
+    # Add AI message
+    ai_msg = ChatMessage(role="assistant", content=ai_response)
+    session.messages.append(ai_msg)
+    session.updated_at = datetime.now(timezone.utc)
+    await session.save()
+
+    return {
+        "user_message": {"role": "user", "content": req.content, "timestamp": user_msg.timestamp.isoformat()},
+        "ai_message": {"role": "assistant", "content": ai_response, "timestamp": ai_msg.timestamp.isoformat()},
+    }
+
+
+@router.get("/{report_id}/history")
+async def get_chat_history(
+    report_id: str, user: User = Depends(get_current_user)
+):
+    """获取聊天历史"""
+    oid = parse_object_id(report_id)
+    report = await Report.get(oid)
+    if not report or report.user_id != user.id:
+        raise HTTPException(status_code=404, detail="报告不存在")
+
+    session = await ChatSession.find_one(
+        ChatSession.user_id == user.id,
+        ChatSession.report_id == report.id,
+    )
+
+    if not session:
+        return {"messages": [], "quick_questions": _get_quick_questions()}
+
+    return {
+        "messages": [
+            {"role": m.role, "content": m.content, "timestamp": m.timestamp.isoformat()}
+            for m in session.messages
+        ],
+        "quick_questions": _get_quick_questions(),
+    }
+
+
+def _get_quick_questions() -> list[str]:
+    return [
+        "这个指标偏高会影响宝宝吗？",
+        "我需要注意什么饮食？",
+        "什么时候需要复查？",
+        "这个结果严重吗？",
+        "有什么改善建议？",
+    ]