feat: 新人初始礼包购买追踪功能

- 数据库：添加 has_purchased_starter_pack 字段到 register_bonus_claims
- 后端：创建静态配置管理套餐信息，支持按国家/地区区分
- 后端：新增 GET /api/v1/points/packages API 返回可用套餐
- 后端：创建 utils/paths.py 统一路径管理
- 前端：动态获取套餐信息，移除硬编码
- 前端：添加 ProductCode 枚举约束，前后端类型安全
- 配置：Profile 默认国家改为 US（ISO 3166-1 alpha-2）
- 文档：更新协议文档说明新 API 和字段

backend/src/v1/points/router.py

@@ -6,7 +6,7 @@ from fastapi import APIRouter, Depends
 
 from core.auth.models import CurrentUser
 from v1.points.dependencies import get_points_service
-from v1.points.schemas import PointsBalanceResponse
+from v1.points.schemas import PackagesResponse, PackageInfo, PointsBalanceResponse
 from v1.points.service import PointsService
 from v1.users.dependencies import get_current_user
 
@@ -26,3 +26,31 @@ async def get_points_balance(
         runCost=result.run_cost,
         canRun=result.can_run,
     )
+
+
+@router.get("/packages", response_model=PackagesResponse)
+async def get_available_packages(
+    service: Annotated[PointsService, Depends(get_points_service)],
+    current_user: Annotated[CurrentUser, Depends(get_current_user)],
+) -> PackagesResponse:
+    result = await service.get_available_packages(
+        user_id=current_user.id,
+        user_email=current_user.email or "",
+    )
+
+    return PackagesResponse(
+        region=result.region,
+        currency=result.currency,
+        packages=[
+            PackageInfo(
+                productCode=pkg.product_code,
+                type=pkg.type.value,
+                price=pkg.price,
+                credits=pkg.credits,
+                isStarter=pkg.is_starter,
+                starterEligible=pkg.starter_eligible,
+                sortOrder=pkg.sort_order,
+            )
+            for pkg in result.packages
+        ],
+    )