feat: 新增后端API路由模块

- 新增faqs.py常见问题路由
- 新增feedback.py反馈路由
- 新增orders.py订单路由
- 新增plans.py套餐路由
- 新增quota.py配额路由
- 新增user.py用户路由
- 更新main.py注册新路由
- 更新requirements.txt添加依赖

api/routers/plans.py

@@ -0,0 +1,149 @@
+"""
+订阅计划相关 API 路由
+"""
+from fastapi import APIRouter, Depends
+from pydantic import BaseModel
+from typing import List, Optional
+from datetime import datetime
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from middleware.auth import get_current_user
+from database.models import User
+from database import get_async_db
+
+router = APIRouter(prefix="/api/plans", tags=["plans"])
+
+
+class PlanResponse(BaseModel):
+    """订阅计划响应"""
+    id: str
+    name: str
+    display_name: str
+    price: float
+    currency: str
+    features: List[str]
+    max_conversations: Optional[int] = None  # None表示无限制
+    max_chapters: Optional[int] = None
+    max_words: Optional[int] = None
+    is_popular: bool = False
+
+
+class CurrentPlanResponse(BaseModel):
+    """当前订阅计划响应"""
+    plan_id: str
+    plan_name: str
+    subscription_type: str
+    expires_at: Optional[str] = None  # 过期时间，None表示永久
+    features: List[str]
+    usage: dict  # 使用情况统计
+
+
+# 预定义的订阅计划
+AVAILABLE_PLANS = [
+    PlanResponse(
+        id="free",
+        name="free",
+        display_name="免费版",
+        price=0.0,
+        currency="CNY",
+        features=[
+            "基础对话功能",
+            "生成回忆录章节",
+            "最多3次对话",
+            "最多10个章节"
+        ],
+        max_conversations=3,
+        max_chapters=10,
+        max_words=50000,
+        is_popular=False
+    ),
+    PlanResponse(
+        id="premium",
+        name="premium",
+        display_name="高级版",
+        price=99.0,
+        currency="CNY",
+        features=[
+            "无限对话",
+            "无限章节",
+            "无限字数",
+            "优先处理",
+            "专属客服支持"
+        ],
+        max_conversations=None,
+        max_chapters=None,
+        max_words=None,
+        is_popular=True
+    )
+]
+
+
+def get_plan_by_type(subscription_type: str) -> Optional[PlanResponse]:
+    """根据订阅类型获取计划信息"""
+    for plan in AVAILABLE_PLANS:
+        if plan.id == subscription_type:
+            return plan
+    return AVAILABLE_PLANS[0]  # 默认返回免费版
+
+
+@router.get("", response_model=List[PlanResponse])
+async def get_plans():
+    """
+    获取所有可用的订阅计划
+    """
+    return AVAILABLE_PLANS
+
+
+@router.get("/current", response_model=CurrentPlanResponse)
+async def get_current_plan(
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_async_db)
+):
+    """
+    获取当前用户的订阅计划信息
+    """
+    plan = get_plan_by_type(current_user.subscription_type)
+    
+    # 计算使用情况
+    from sqlalchemy import select, func
+    
+    # 统计对话数量
+    from database.models import Conversation
+    stmt = select(func.count(Conversation.id)).where(
+        Conversation.user_id == current_user.id
+    )
+    result = await db.execute(stmt)
+    conversation_count = result.scalar() or 0
+    
+    # 统计章节数量
+    from database.models import Chapter
+    stmt = select(func.count(Chapter.id)).where(
+        Chapter.user_id == current_user.id
+    )
+    result = await db.execute(stmt)
+    chapter_count = result.scalar() or 0
+    
+    # 统计总字数
+    stmt = select(func.sum(func.length(Chapter.content))).where(
+        Chapter.user_id == current_user.id
+    )
+    result = await db.execute(stmt)
+    total_words = result.scalar() or 0
+    
+    usage = {
+        "conversations": conversation_count,
+        "chapters": chapter_count,
+        "words": total_words,
+        "max_conversations": plan.max_conversations,
+        "max_chapters": plan.max_chapters,
+        "max_words": plan.max_words
+    }
+    
+    return CurrentPlanResponse(
+        plan_id=plan.id,
+        plan_name=plan.display_name,
+        subscription_type=current_user.subscription_type,
+        expires_at=None,  # 目前没有过期时间概念
+        features=plan.features,
+        usage=usage
+    )