Problem

Follow-up to #263. The first fix (!cancelled() on docker-build) was insufficient. GitHub Actions propagates skipped status transitively through the entire needs chain. Even though docker-build ran successfully, semantic-release was still skipped because review-thread-gate (transitive dependency) was skipped.

Fix

Instead of sprinkling !cancelled() on every downstream job, make the gate job always run:

• Remove if: github.event_name == 'pull_request' from the gate job
• Add early exit inside the script for non-PR events, outputting allow_heavy=true
• Simplify docker-build condition to just check allow_heavy output
• Revert the !cancelled() approach from fix(ci): unblock release pipeline on push to main #264 as it's insufficient

This way no job in the chain is ever skipped, preventing transitive propagation.