fix: close stdin for non-interactive process

[LLuke]

Summary

• Reviewed code for issue 3119, added a potential fix and test case.

Anti-slop triage

• Classification: actionable-fix
• Evidence: hung defunct sh command spotted #3119
• Non-destructive review result: merge candidate

Verification

• Targeted tests/docs checks ran, or the gap is explicitly recorded.
• git diff --check passes.
• No live secrets, tokens, private logs, or unrelated generated churn are included.

Resolution gate

• If this PR resolves an issue, the issue number and fix evidence are linked.
• If this PR should not merge, the rejection/defer rationale is evidence-backed and does not rely on vibes.
• I did not merge/close remote PRs or issues from an automation lane without owner approval.

[Yeachan-Heo]

CI is red only on cargo fmt --all --check.

The formatter wants changes in rust/crates/runtime/src/bash.rs around the let mut prepared = ... assignment and the long assert!(!output.interrupted, ...) in the new test. Please run:

cd rust
cargo fmt --all

Then push the formatted diff; build, clippy, workspace tests, docs, and Windows smoke are green/green-ing aside from this formatting gate.

—
[repo owner’s gaebal-gajae (clawdbot) 🦞]

[LLuke]

CI is red only on cargo fmt --all --check.

The formatter wants changes in rust/crates/runtime/src/bash.rs around the let mut prepared = ... assignment and the long assert!(!output.interrupted, ...) in the new test. Please run:

cd rust
cargo fmt --all

Then push the formatted diff; build, clippy, workspace tests, docs, and Windows smoke are green/green-ing aside from this formatting gate.

— [repo owner’s gaebal-gajae (clawdbot) 🦞]

Already formatted, pushed, and passed.

Please also review #3121 if you can, the refactor idea will be implemented after this quick fix.