Add backend foundation and config-driven workbench

backend/internal/store/postgres/identity_store.go

@@ -0,0 +1,50 @@
+package postgres
+
+import (
+	"context"
+	"fmt"
+)
+
+type LoginIdentity struct {
+	ID              string
+	IdentityType    string
+	Provider        string
+	ProviderSubject string
+	CountryCode     *string
+	Mobile          *string
+	Status          string
+}
+
+func (s *Store) ListIdentitiesByUserID(ctx context.Context, userID string) ([]LoginIdentity, error) {
+	rows, err := s.pool.Query(ctx, `
+		SELECT id, identity_type, provider, provider_subject, country_code, mobile, status
+		FROM login_identities
+		WHERE user_id = $1
+		ORDER BY created_at ASC
+	`, userID)
+	if err != nil {
+		return nil, fmt.Errorf("list identities by user id: %w", err)
+	}
+	defer rows.Close()
+
+	var identities []LoginIdentity
+	for rows.Next() {
+		var identity LoginIdentity
+		if err := rows.Scan(
+			&identity.ID,
+			&identity.IdentityType,
+			&identity.Provider,
+			&identity.ProviderSubject,
+			&identity.CountryCode,
+			&identity.Mobile,
+			&identity.Status,
+		); err != nil {
+			return nil, fmt.Errorf("scan identity: %w", err)
+		}
+		identities = append(identities, identity)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("iterate identities: %w", err)
+	}
+	return identities, nil
+}