Optimize trigger conditions for CI workflows

[lnfjpt]

As titled.

[github-actions]

🤖 Auto-triage: linked as sub-issue of #257 — Grouping adhoc issues (confidence: high).

Reason: CI workflow trigger optimization is a small cross-cutting CI/build-infra one-off that does not fit any specific subsystem umbrella.

If this is wrong, please unlink and re-assign — your correction improves this bot.