fix(executor): increase buffer size for stream scanners to 50MB across multiple executors

internal/runtime/executor/codex_executor.go

@@ -205,7 +205,7 @@ func (e *CodexExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Au
 			}
 		}()
 		scanner := bufio.NewScanner(httpResp.Body)
-		scanner.Buffer(nil, 20_971_520)
+		scanner.Buffer(nil, 52_428_800) // 50MB
 		var param any
 		for scanner.Scan() {
 			line := scanner.Bytes()