Summary

Makes the weekly pstack changelog sync robust against missed commits without changing the workflow schedule.

• sync-pstack.py now paginates through up to 100 pages (up from 2) and uses the since timestamp of the latest entry, so it still catches new history if the last recorded SHA is rebased or no longer on the branch.
• Added a fallback warning when the last SHA is not found in fetched history; the sync continues from since instead of silently truncating at the page limit.
• Fixed new-entry count to report actual unique additions.
• sync-pstack.yml now captures the script output to the workflow step summary and flags warnings, so missed-commit cases are visible in the Actions run.
• Ran the script locally to catch the 8 pstack commits that landed since the last sync on 2026-07-10.

Trigger behavior is unchanged: still runs every Monday at 09:00 UTC and on workflow_dispatch.

Link to Devin session: https://app.devin.ai/sessions/041012c8528a46e2955cb099dd3b4eb4
Requested by: @HustleCoding