v2.9.9 — CHANGELOG now complete

Changed

• CHANGELOG Backfill: Reconstructed the missing 2.6.0–2.9.1 entries from the GitHub Release notes. CHANGELOG.md had stalled at 2.5.8 while releases reached 2.9.x; it is now complete and continuous through 2.9.9 (2.6.5 was never released).

Docs-only; no code or site change.

🤖 Generated with Claude Code