fix: keep PR title check required after rebases

[zeitlinger]

Summary

• rerun the PR title check after PR branch updates and reopen events
• give the title check a unique status context so it cannot be satisfied by the regular lint job

This closes the workflow gap observed on #2410, where Renovate rebased the branch, the failed title check remained attached to the previous SHA, and the successful regular lint job satisfied the required lint context.

After this PR merges, pr-title must be added as a distinct required check in the main-branch ruleset. Adding it before merge would block every existing PR because their merge commits still use the old lint job name.

Validation

• mise run lint:fix
• mise run lint
• pr-title check passed on this PR with the new job name