feat: 修复 H5 底部导航覆盖 + 更新项目进度文档

## H5 底部导航修复 (Bug #10)
- 精简 App.vue，移除重复 tabbar，仅保留全局样式
- uni-page 设置 height: calc(100% - 50px) + overflow-y: auto
- 内容区域精确停在底部导航上方，独立滚动不再叠加
- 恢复 custom-tab-bar 组件

## 项目进度文档
- PROGRESS.md 更新至 10 个 Bug 修复
- 新增 H5 底部导航修复记录
- 新增历史变更条目

backend/app/api/v1/onboarding.py

@@ -0,0 +1,43 @@
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+from typing import Annotated
+from pydantic import BaseModel
+from app.database import get_db
+from app.services.onboarding import OnboardingService
+from app.api.v1.deps import get_current_user_id
+
+router = APIRouter()
+
+
+class OnboardingRequest(BaseModel):
+    name: str
+    description: str
+    category: str = ""
+    target: str = "US importers"
+
+
+@router.get("/status")
+async def get_status(
+    user_id: str = Depends(get_current_user_id),
+    db: Annotated[AsyncSession, Depends(get_db)] = None,
+):
+    service = OnboardingService(db)
+    return await service.check_status(user_id)
+
+
+@router.post("/product")
+async def create_first_product(
+    data: OnboardingRequest,
+    user_id: str = Depends(get_current_user_id),
+    db: Annotated[AsyncSession, Depends(get_db)] = None,
+):
+    if not data.name.strip():
+        raise HTTPException(status_code=400, detail="Product name is required")
+    service = OnboardingService(db)
+    return await service.generate_first_product(
+        user_id=user_id,
+        name=data.name.strip(),
+        description=data.description.strip(),
+        category=data.category,
+        target=data.target,
+    )