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/admin_service.go

@@ -22,6 +22,10 @@ type AdminService interface {
 	UpdateUserBalance(ctx context.Context, userID int64, balance float64, operation string, notes string) (*User, error)
 	GetUserAPIKeys(ctx context.Context, userID int64, page, pageSize int) ([]APIKey, int64, error)
 	GetUserUsageStats(ctx context.Context, userID int64, period string) (any, error)
+	// GetUserBalanceHistory returns paginated balance/concurrency change records for a user.
+	// codeType is optional - pass empty string to return all types.
+	// Also returns totalRecharged (sum of all positive balance top-ups).
+	GetUserBalanceHistory(ctx context.Context, userID int64, page, pageSize int, codeType string) ([]RedeemCode, int64, float64, error)
 
 	// Group management
 	ListGroups(ctx context.Context, page, pageSize int, platform, status, search string, isExclusive *bool) ([]Group, int64, error)
@@ -522,6 +526,21 @@ func (s *adminServiceImpl) GetUserUsageStats(ctx context.Context, userID int64,
 	}, nil
 }
 
+// GetUserBalanceHistory returns paginated balance/concurrency change records for a user.
+func (s *adminServiceImpl) GetUserBalanceHistory(ctx context.Context, userID int64, page, pageSize int, codeType string) ([]RedeemCode, int64, float64, error) {
+	params := pagination.PaginationParams{Page: page, PageSize: pageSize}
+	codes, result, err := s.redeemCodeRepo.ListByUserPaginated(ctx, userID, params, codeType)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	// Aggregate total recharged amount (only once, regardless of type filter)
+	totalRecharged, err := s.redeemCodeRepo.SumPositiveBalanceByUser(ctx, userID)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	return codes, result.Total, totalRecharged, nil
+}
+
 // Group management implementations
 func (s *adminServiceImpl) ListGroups(ctx context.Context, page, pageSize int, platform, status, search string, isExclusive *bool) ([]Group, int64, error) {
 	params := pagination.PaginationParams{Page: page, PageSize: pageSize}

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