test: validate downstream package-manager dispatch chain end-to-end

Empty commit to fire snapshot.yml -> release.yml -> repository_dispatch
to homebrew-wheels and chocolatey-wheels. Tests:

  - DOWNSTREAM_DISPATCH_TOKEN with corrected Contents:write scope
  - workflow_call secret passthrough (#2324)
  - AUTO_MERGE_PAT propagating events on both downstream repos
  - choco publish-on-merge firing automatically after auto-update merge

Expected: ~15-20 min for the full chain to complete with no manual
nudges. Resulting wheels v0.3.7.<runNumber> on community.chocolatey.org.

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

Author: bpamiri