ci(edge): run Windows checks and releases on Node 24.21.0, past the libuv exit abort

[pawaca]

Fixes the intermittent Windows CI crash (exit code 3221226505 = 0xC0000409) by moving the pinned Node from 24.15.0 to 24.21.0.

Evidence

Across the last 80 Edge CI runs, edge / windows release checks aborted with 0xC0000409 eight times:

• Five crashed while wrangler exited after a bundling error. Their logs print the cause:
  Assertion failed: !(handle->flags & UV_HANDLE_CLOSING), file src\win\async.c, line 76.
• Three crashed inside session.integration.mjs within 2–15 s of a mode's start, before any test output. That is where wrangler's unstable_dev starts and stops the released-state seeder. They exited with the same status; no assertion text reached the log.

This is the known Node bug nodejs/node#56645. A platform worker thread posts a delayed task after the scheduler's uv_async handle started closing at exit, so Windows libuv aborts. nodejs/node#61999 ("src: fix libuv assertion on windows") fixed it in 24.20.0 (CHANGELOG_V24.md). The same 0xC0000409 hits release publish jobs, which run the same checks on Windows; today it would fail a tag and force a new version number.

Why 24.21.0, not 24.20.0

release-edge.yml stayed on 24.15.0 because 24.16+ could abort Windows file watchers when runner temp uses an 8.3 short path, until nodejs/node#65118. That fix shipped in 24.21.0. 24.21.0 is the first release with both fixes, so .node-version, edge-ci.yml's WINDOWS_NODE_VERSION, and release-edge.yml's NODE_VERSION all move to it. The stale comment is replaced with one covering both.

Validation

This PR's own edge / windows release checks runs on 24.21.0. The crash is intermittent (about 1 in 10 runs here), so I will rerun that job a few times before merging and report the results.

🤖 Generated with Claude Code

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-07T14:20:08.739733Z	c08d9f6	PR opened

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[pawaca]

Validation on Node v24.21.0 (confirmed in the job log): edge / windows release checks passed 4 of 4 runs of run 37635560292 (the first run plus 3 job reruns). For comparison, the crash hit 8 of the last 80 Windows runs on 24.15.0. The file-watcher concern behind the old 24.15.0 pin (nodejs/node#65118) did not show in these runs either.