REPL 空行会静默退出，不符合"Type q to quit"横幅，并且会被 VS Code 的 stdin 注入放大

On its own, this is a minor convention mismatch. It becomes painful when combined with a known VS Code bug: the ZZTERM12ZZ extension injects an environment-activation command into every new terminal, and with `"console": "integratedTerminal"`, that injection often arrives *after* the debugged program is already blocked in `input()`, so the program consumes it. See microsoft/vscode-ZZTERM13ZZ#25744 (open) and #9374 (closed).