Play Framework

ci: retarget workflow push/PR triggers from master to main

The default branch in this fork is main, but the build-test, CodeQL,
and release-drafter workflows all still filtered on master — inherited
from upstream playframework/play1. As a result none of these workflows
have ever fired on push to main, leaving the README's Build Status
badge stuck on "no status". Retarget all three triggers to main.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>