Refactor gRPC adapter to use connection pool and improve error handling in product retrieval

internal/marketplace/repository_db.go

@@ -2,15 +2,14 @@ package marketplace
 
 import (
 	"context"
-	"github.com/jackc/pgx/v5"
 	"sipro-mps/internal/marketplace/db"
 )
 
 type dbRepository struct {
-	conn *pgx.Conn
+	conn db.DBTX
 }
 
-func NewDBRepository(conn *pgx.Conn) Repository {
+func NewDBRepository(conn db.DBTX) Repository {
 	return &dbRepository{conn: conn}
 }