fix: Guard GITHUB_OUTPUT, surface GraphQL errors and tighten is-int

[hustcer]

Fix several issues that only show up outside of Github Actions or on error paths:

• Guard $env.GITHUB_OUTPUT behind a set-action-output helper, so that create/close no longer fail with a column-not-found error when run locally via just or during manual debugging
• Add check-graphql-errors in query.nu and use it in both query-issue-status (which previously did no error checking at all) and query-pr-closing-issues (which discarded the error payload); the real diagnostics are now printed and the first message is carried in error make
• Drop the redundant --remove-milestone calls on the --force path: the REST PATCH is already overwrite semantics, and the extra call created a visible intermediate state plus a duplicated "will be ignored" message
• Make is-int match ASCII digits only, since \d in Rust regex covers the whole Unicode Nd category and accepted input like '１２３' as a milestone number
• Import has-ref from common.nu in release.nu instead of relying on the Justfile overlay
• Replace the long-removed register -e json with plugin add in _setup

closes #171

Summary by CodeRabbit

• Bug Fixes

  • Improved milestone replacement behavior when force-updating issues and pull requests.
  • Added clearer GraphQL error reporting for issue and pull request operations.
  • Improved validation of milestone numbers to reject invalid characters.
  • Made GitHub Actions output handling safer when workflow output is unavailable.

• Compatibility

  • Updated setup support for Nushell v0.93.
  • Improved release workflow reliability.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 91c802d5-97ae-4d05-8f9b-8cb4b5c662fa

📥 Commits

Reviewing files that changed from the base of the PR and between b57a2e2 and 67a0f47.

📒 Files selected for processing (4)

• Justfile
• nu/milestone.nu
• nu/query.nu
• nu/release.nu

Included review availability: Your plan provides up to 5 included reviews per hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

The pull request updates Nushell setup compatibility, milestone mutation behavior, GitHub Actions output handling, integer validation, GraphQL error reporting, and release-script imports.

Changes

Nushell workflow updates

Layer / File(s)	Summary
Shared GraphQL error validation nu/query.nu	A shared helper reports GraphQL diagnostics and raises the first error message. Issue-status and pull-request queries use the helper before reading results.
Milestone updates and action outputs nu/milestone.nu	Forced updates rely on replacement PATCH operations. Milestone outputs use guarded writes, and integer validation accepts only ASCII digits.
Nushell setup and release wiring Justfile, nu/release.nu	The setup recipe uses plugin add. The release script imports has-ref from common.nu.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 67a0f

The PR makes localized error-handling, environment-compatibility, command cleanup, input-validation, and setup changes; no actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main fixes: guarding GITHUB_OUTPUT, surfacing GraphQL errors, and tightening integer validation.
Linked Issues check	✅ Passed	The changes implement all stated objectives for issue #171, including output guarding, GraphQL diagnostics, milestone handling, ASCII validation, imports, and plugin setup.
Out of Scope Changes check	✅ Passed	All changed files and updates directly support the objectives described in issue #171 and the pull request summary.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (4 skipped: 4 unsupported.)

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch hotfix

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