[turlamai]

Changes

• Cancel superseded CI by workflow/event/ref.
• Execute formatting checks only on Linux/Racket 9.3 instead of six redundant OS/version combinations.
• Move three informational, non-gating performance baseline jobs to a weekly/manual Performance Baseline workflow. Packaging, WebView E2E and Racket-version compatibility remain in PR CI.
• Document the new cadence.

Verify before merge

• CI retains six test jobs, three WebView E2E jobs and three packaging jobs; formatting runs once.
• Manually dispatch the new baseline workflow and confirm the three JSON artifacts.
• If branch protection requires the old informational baseline status, update that check policy first.
• Compare runner queue and execution time before/after.