[dunglas]

Prepares required status checks on main.

• Tests passed and Sanitizers passed aggregate their workflow's jobs. Skipped jobs count as passing, failed or cancelled ones fail the gate.
• Docs-only PRs used to skip these workflows entirely through paths-ignore, so a required check would stay pending forever. A Detect changes job now skips the jobs instead, and the gate still reports.
• The PHP 8.6 job keeps continue-on-error, so php-src master breakage doesn't block merges.
• The Windows job is renamed Windows build: build also exists in the Docker workflow, where it is skipped on PRs and could satisfy a required check.

Once merged, the ruleset can require Lint Code Base, Tests passed, Sanitizers passed and Windows build.