feat(api): Add compatibility layer for API v1

pkg/citydb/provider.go

@@ -14,11 +14,16 @@ import (
 )
 
 type Provider struct {
-	db *goqu.Database
+	db  *goqu.Database
+	own bool
 }
 
 func New(db *goqu.Database) Provider {
-	return Provider{db: db}
+	return Provider{db: db, own: false}
+}
+
+func NewWithConn(conn *sql.DB) Provider {
+	return Provider{db: goqu.New("sqlite3", conn), own: false}
 }
 
 func Open(path string) (Provider, error) {
@@ -31,10 +36,14 @@ func Open(path string) (Provider, error) {
 		return Provider{}, fmt.Errorf("failed to connect to cities database: %w", err)
 	}
 
-	return New(goqu.New("sqlite3", conn)), nil
+	return Provider{db: goqu.New("sqlite3", conn), own: true}, nil
 }
 
 func (p Provider) Close() error {
+	if !p.own {
+		return nil
+	}
+
 	if err := p.db.Db.(*sql.DB).Close(); err != nil {
 		return fmt.Errorf("failed to close cities database: %w", err)
 	}