Add interface do DB driver to repository

This abstraction is needed to add transactional cleanup in the future.

user_repository.go

@@ -12,12 +12,17 @@ import (
 "github.com/google/uuid"
 )
 
-func NewUserRepository(db *sql.DB) *UserRepository {
+type DB interface {
+QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row
+ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
+}
+
+func NewUserRepository(db DB) *UserRepository {
 return &UserRepository{db: db}
 }
 
 type UserRepository struct {
-db *sql.DB
+db DB
 }
 
 func (r *UserRepository) ReadUser(ctx context.Context, userID uuid.UUID) (User, error) {