feat(admin): add user balance/concurrency history modal

- Add new API endpoint GET /admin/users/:id/balance-history with pagination and type filter
- Add SumPositiveBalanceByUser for calculating total recharged amount
- Create UserBalanceHistoryModal component with:
  - User info header (email, username, created_at, current balance, notes, total recharged)
  - Type filter dropdown (all/balance/admin_balance/concurrency/admin_concurrency/subscription)
  - Quick deposit/withdraw buttons
  - Paginated history list with icons and colored values
- Add instant tooltip on balance column for better UX
- Add z-index prop to BaseDialog for modal stacking control
- Update i18n translations (zh/en)

backend/internal/service/redeem_service.go

@@ -49,6 +49,11 @@ type RedeemCodeRepository interface {
 	List(ctx context.Context, params pagination.PaginationParams) ([]RedeemCode, *pagination.PaginationResult, error)
 	ListWithFilters(ctx context.Context, params pagination.PaginationParams, codeType, status, search string) ([]RedeemCode, *pagination.PaginationResult, error)
 	ListByUser(ctx context.Context, userID int64, limit int) ([]RedeemCode, error)
+	// ListByUserPaginated returns paginated balance/concurrency history for a specific user.
+	// codeType filter is optional - pass empty string to return all types.
+	ListByUserPaginated(ctx context.Context, userID int64, params pagination.PaginationParams, codeType string) ([]RedeemCode, *pagination.PaginationResult, error)
+	// SumPositiveBalanceByUser returns the total recharged amount (sum of positive balance values) for a user.
+	SumPositiveBalanceByUser(ctx context.Context, userID int64) (float64, error)
 }
 
 // GenerateCodesRequest 生成兑换码请求