* ci: skip PR runs when targeting a non-main base branch
Adds `branches: [main]` to the `pull_request:` trigger of each workflow
that runs on PRs (CI, regression, Windows render verification, Docs,
Catalog Previews). PRs whose base is something other than main — typical
for stacked PRs — no longer trigger these workflows.
On a 5-PR Graphite stack this turns 5× CI runs into 1× (when the tip
of the stack reaches main). When a child PR is rebased/promoted so its
base becomes main, CI fires as normal.
publish.yml and the default CodeQL setup are untouched: publish already
filters to main, and CodeQL is default-setup (org UI, not a repo YAML).
* chore(ci): fix oxfmt formatting on renovate.json
Same drive-by as #423. Renovate's config-migration PR #422 landed
unformatted (Renovate bot skips lefthook), so every PR branched from
current main fails `bun run format:check`. Whichever of #423 / #426
merges first cleans it up.