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/silent_pattern.py

@@ -1,6 +1,5 @@
 from fastapi import APIRouter, Depends, HTTPException
 from sqlalchemy.ext.asyncio import AsyncSession
-from typing import Annotated
 from app.database import get_db
 from app.services.silent_pattern import SilentPatternService
 from app.api.v1.deps import get_current_user_id
@@ -11,7 +10,7 @@ router = APIRouter()
 @router.get("/risk-analysis")
 async def get_silent_risk_analysis(
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = SilentPatternService(db)
     risks = await service.analyze_silent_risk(user_id)
@@ -27,7 +26,7 @@ async def get_silent_risk_analysis(
 async def get_followup_suggestions(
     customer_id: str,
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = SilentPatternService(db)
     suggestions = await service.get_suggestions(user_id, customer_id)