feat: add database wrapper interfaces for mssql and postgres

Introduce a DB dialect interface and per-dialect wrappers that expose connection, query and column type operations with pre/post SQL hooks.

internal/app/db/postgres.go

@@ -26,3 +26,22 @@ func Close(pool *pgxpool.Pool) {
 		pool.Close()
 	}
 }
+
+type PostgresDbWrapper struct {
+	db *pgxpool.Pool
+}
+
+func NewPostgresDbWrapper(db *pgxpool.Pool) DbWrapper {
+	return &PostgresDbWrapper{db: db}
+}
+
+func (wrapper *PostgresDbWrapper) Exec(ctx context.Context, query string, args ...any) (DbWrapperResult, error) {
+	result, err := wrapper.db.Exec(ctx, query, args...)
+	if err != nil {
+		return DbWrapperResult{}, err
+	}
+
+	return DbWrapperResult{
+		AffectedRows: result.RowsAffected(),
+	}, nil
+}