feat: silent wechat login, marketing tab optimization, admin page foundation

- Add silent WeChat login for MP/browser environments
- Fix Python 3.6 compatibility (remove typing.Annotated usage)
- Marketing page: tab-based content generation with category support
- Translate page: add auto-detect language default
- Homepage: add TTS playback, announcement ticker, remove redundant quick-actions
- Fix FAB button overlap with custom tabbar on customers/quotation pages
- Make openai/anthropic imports lazy for Python 3.6 compat

backend/app/api/v1/push.py

@@ -1,6 +1,6 @@
 from fastapi import APIRouter, Depends, HTTPException
 from sqlalchemy.ext.asyncio import AsyncSession
-from typing import Annotated, Optional
+from typing import Optional
 from pydantic import BaseModel
 from app.database import get_db
 from app.services.push import PushService
@@ -20,7 +20,7 @@ class DeviceRegisterRequest(BaseModel):
 async def register_device(
     data: DeviceRegisterRequest,
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = PushService(db)
     device = await service.register_device(
@@ -41,7 +41,7 @@ async def register_device(
 async def unregister_device(
     data: dict,
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     client_id = data.get("client_id")
     if not client_id:
@@ -56,7 +56,7 @@ async def unregister_device(
 @router.get("/devices")
 async def list_devices(
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = PushService(db)
     devices = await service.get_user_devices(user_id)