feat(web-session): add Codex skill browser and CodeMirror composer

feat(ui): show project initials in session badges

feat(web-session): notify only when re-clicking the active draft

perf(api): optimize static asset cache headers

style(web-session): flatten sidebar session markers

fix(web-session): preserve Codex command groups across reasoning

Keep Codex compact-tool grouping intact when reasoning appears between command executions, filter empty Codex reasoning on the backend, and keep Claude behavior unchanged.

Merge remote-tracking branch 'origin/master'

fix(ui): remove stray settings template tags

feat(websession): add raw toggle to timeline cards

fix(web-session): stabilize synced history rendering