Add AIR status and termination parity

[ben-hansen-db]

Changes

• Expose failure termination reasons in JSON and human output.
• Recognize timed-out runs as terminal failures.
• Display pending first-task states without changing machine-readable status.

Why

Close the remaining status and termination gaps with the Python AIR CLI.

Tests

• go test ./experimental/air/cmd

This PR was written with Codex.

[eng-dev-ecosystem-bot]

Integration test report

Commit: 00f511d

Run: 33127290621

	Env	💚​RECOVERED	🙈​SKIP	✅​pass	🙈​skip	Time
💚​	aws linux	1	1	274	1194	4:13
💚​	aws windows	1	1	276	1192	3:53
💚​	azure linux	1	1	273	1194	4:16
💚​	azure windows	1	1	275	1192	3:39
💚​	gcp linux	1	1	274	1194	4:41
💚​	gcp windows	1	1	276	1192	3:31

	Test Name	aws linux	aws windows	azure linux	azure windows	gcp linux	gcp windows
💚​	TestAccept	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R
🙈​	TestAccept/ssh/connection	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S

Top 3 slowest tests (at least 2 minutes):

duration	env	testname
3:48	aws windows	TestAccept
3:34	azure windows	TestAccept
3:20	gcp windows	TestAccept

[github-actions]

Approval status: pending

/experimental/air/ - approved by @vinchenzo-db

10 files changed

General files (require maintainer)

Files: .nextchanges/cli/air-status-parity.md
Based on git history:

• @janniklasrose -- recent work in .nextchanges/cli/

_{Any maintainer (@andrewnester, @anton-107, @denik, @pietern, @shreyas-goenka, @simonfaltum, @renaudhartert-db, @janniklasrose, @lennartkats-db, @rugpanov, @rclarey) can approve all areas.
See OWNERS for ownership rules.}