Re-enable scheduled sync after 2026-06-09 recovery (ADO 5347122) (microsoft-foundry#499)

Restores the nightly 06:00 UTC `schedule` block in `sync-to-public.yml`
that PR microsoft-foundry#484 commented out on 2026-06-08. The guard bug that motivated
the pause (ADO 5347121) was fixed by PR microsoft-foundry#493, and the 2026-06-09
recovery sequence (private PR microsoft-foundry#495 + public PR microsoft-foundry#767)
was validated end-to-end by a successful `workflow_dispatch` real run:
https://github.com/microsoft-foundry/foundry-samples-pr/actions/runs/27253358355

Sync is operationally healthy again; the first scheduled run after merge
will land at the next 06:00 UTC.

Closes ADO 5347122.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people

.github/workflows/sync-to-public.yml

@@ -1,11 +1,8 @@
 name: Sync to Public Repo
 
 on:
-  # Scheduled sync PAUSED 2026-06-08 pending fix for Path B protected-paths guard
-  # architectural bug. See docs/repo-sync-automation.md (Known issues).
-  # Re-enable by uncommenting the schedule block below after the guard fix lands.
-  # schedule:
-  #   - cron: '0 6 * * *' # Nightly at 6:00 UTC
+  schedule:
+    - cron: '0 6 * * *' # Nightly at 6:00 UTC
   workflow_dispatch:
     inputs:
       dry_run: