fix(coding-agent): preserve interactive session confirmation

[beengineer500]

Summary

• Prevent the readline close fallback from overriding an answer already received by promptConfirm().
• Preserve y/yes approval and n/empty/EOF rejection.
• Add deterministic regression coverage and the required coding-agent change tracker entry.

Reproduction

When resuming a session from another project with --session, answering y or yes incorrectly aborted the operation:

Fork this session into current directory? [y/N] y
Aborted.

Root cause

rl.close() was called inside the readline question callback before resolving the answer. The emitted close event resolved the promise with false before the y/yes result could take effect.

The fix uses a settled guard so the EOF fallback remains active without overriding an answer that has already been received.

Testing

• npm run build
• npm --prefix packages/coding-agent test -- test/suite/regressions/interactive-session-confirmation.test.ts — 5 passed
• npm --prefix packages/coding-agent test -- test/suite/regressions/756-session-cross-project-resume.test.ts — 2 passed
• npm run check
• node .agents/skills/senpi-qa/scripts/cli-smoke.mjs --self-test — 8/8 passed
• Manual interactive terminal QA: entering y returned a forked session manager with the target session created in the destination project.

Related

This is related to #756, but is distinct: #756 covers non-interactive stdin handling, while this PR fixes the interactive readline confirmation race.

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Summary by cubic

Preserves interactive confirmation during cross-project session resolution. Previously, y/yes approvals were overridden by a readline close event and aborted; now y/yes approves, while n/empty/EOF rejects.

• Guard the readline close fallback so it rejects only when no answer was received; settle once in promptConfirm.
• Export promptConfirm and add regression tests for y, yes, n, empty input, and EOF; update the changes.md tracker entry.

^{Written for commit 1ffd426. Summary will update on new commits.}