(ci): cut workflow cost: generic tests on Linux, platform-specific ones on Windows #1026

Why

GitHub disabled the workflows as too costly, reported by Jean-Baptiste on 2026-11-07; no run started from 11-04 to 11-07. October cost $881 gross ($0 net, public repo): storage $291, Windows $259, macOS $159, Linux $149, ARM $24. There are 1,822 GB of live artifacts at 90-day retention, 95 % from non-tag runs.

Decided by Jean-Baptiste in person, 2026-11-07

Generic Node tests run on Linux; Windows and macOS keep only what is platform-specific.

Slice 1:

• retention-days: 3 for PRs, 14 otherwise.
• PR builds only when packaging changes, plus workflow_dispatch to build an installer on demand.
• Cancel runs superseded on a PR; tags never cancel.
• Timeouts: test 25 min, others 10.
• Drop test (20, windows-2022).
• Push to main keeps a Windows job.
• Tag builds stay full, with all 19 assets.

Slice 2: Windows runs a platform-specific test set, with a guard so a new platform-dependent test cannot be left out.

Existing non-tag artifacts are being purged separately.

Separate

Flaky tests measured on main: setScheduleEnabled (21), checked save timeout (8), e2e background Delete (9).