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/product.py

@@ -1,6 +1,6 @@
 from fastapi import APIRouter, Depends, HTTPException, Query
 from sqlalchemy.ext.asyncio import AsyncSession
-from typing import Annotated, Optional
+from typing import Optional
 from app.database import get_db
 from app.services.product import ProductService
 from app.api.v1.deps import get_current_user_id
@@ -44,7 +44,7 @@ async def list_products(
     page: int = Query(1, ge=1),
     size: int = Query(20, ge=1, le=100),
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = ProductService(db)
     return await service.list_products(user_id, category, page, size)
@@ -54,7 +54,7 @@ async def list_products(
 async def get_product(
     product_id: str,
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = ProductService(db)
     product = await service.get_product(user_id, product_id)
@@ -67,7 +67,7 @@ async def get_product(
 async def create_product(
     data: ProductCreate,
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = ProductService(db)
     product = await service.create_product(user_id, data.dict())
@@ -79,7 +79,7 @@ async def update_product(
     product_id: str,
     data: ProductUpdate,
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = ProductService(db)
     product = await service.update_product(user_id, product_id, data.dict(exclude_unset=True))
@@ -92,7 +92,7 @@ async def update_product(
 async def delete_product(
     product_id: str,
     user_id: str = Depends(get_current_user_id),
-    db: Annotated[AsyncSession, Depends(get_db)] = None,
+    db: AsyncSession = Depends(get_db),
 ):
     service = ProductService(db)
     deleted = await service.delete_product(user_id, product_id)