Release v0.2.9 #416

Tracking issue for the v0.2.9 release. Procedure: prompts/pg_durable-release.md.

Cut line: v0.2.8...584298de, including #418, plus release-preparation PR #417. Rebase and lease-protected branch update approved by Gokhan Gulbiz (@gokhangulbiz) on 2026-10-07.
Tag commit: pending preparation merge and exact-main CI.
Published by: pending approval.

• Cut line confirmed through Schema-qualify functions/types/etc in our SQL wherever possible #418 (recheck main before tagging)
• Changelog merged (PR #417, head 4907992; required review and merge approval pending)
• Version/upgrade-script sanity (0.2.9 metadata unchanged; shipped migrations unchanged; recheck on final SHA)
• PGXN credentials configured (PGXN_USERNAME, PGXN_PASSWORD names verified; credential validity not yet established)
• CI green on tag commit (new baseline main CI green; rebased PR CI green at 49079928; eventual merged-main CI pending)
• Tagged v0.2.9 -> draft Release (tag workflow must pass exact-candidate PG17/PG18 package validation)
• Release published (approved by: pending; includes automatic GHCR and PGXN publication)
• GHCR images confirmed
• PGXN release confirmed
• Next-cycle PR opened