docs: Update README for v2.19.0 release features

feat: GUI v2.17.0 build+tests+bridge

Co-authored-by: Cursor <cursoragent@cursor.com>

feat: merge upstream openai/codex (226 commits) - v2.16.0 Upstream Sy…

…nc & Security Hardening

docs: Reorganize and update README, add related documentation and ima…

…ge, and include v2.15.1 announcements.

Release v2.14.1 - CI/CD Stability & GUI Enhancement

Refactor chatwidget, fix visibility issues, OtelEventManager signatur…

…e, and unused imports to enable successful build of v2.14.0

Release 0.99.0-alpha.9