Allow docs snapshot commits to trigger Pages publish; skip only self-publish commits

[Copilot]

Versioned docs snapshots (for example docs: snapshot 1.2 release docs) were committed to main but never published because the deploy job blocked all runs by github-actions[bot]. This change narrows the guard to block only the workflow’s own generated publish commit, so snapshot commits now publish correctly without introducing recursion.

• Root-cause alignment

  • Removed actor-based suppression from deploy-docs.yml that prevented bot-authored snapshot pushes from running deploy.

• Deploy trigger guard (narrow + loop-safe)

  • Replaced broad bot exclusion with a commit-message gate that skips only commits starting with docs: publish static site.
  • Kept guard null-safe for push payload variations.

• Scope

  • Single-file workflow change in .github/workflows/deploy-docs.yml; no docs/source/build logic changes.

jobs:
  publish:
    if: "github.event_name != 'push' || (github.event.head_commit == null || !startsWith(github.event.head_commit.message, 'docs: publish static site'))"