* stage-3955: blur composer on Escape for j/k nav + IME guard (Opus nit)
* stage-3955: update test to match IME-guarded blur branch
* Release OX: blur composer on Escape for j/k message nav (#3952)
Self-rebased TomBanksAU's #3955 onto v0.51.436; full Codex+Opus+suite gate.
Escape now blurs the focused composer so j/k session-nav works, after higher-
priority Escape actions run; dropdown-Escape stops propagation; IME-composition
guarded (Opus nit). Also restored the v0.51.434/435 CHANGELOG headings that an
earlier batch left folded under v0.51.436 (hygiene fix).
Co-authored-by: TomBanksAU <TomBanksAU@users.noreply.github.com>
---------
Co-authored-by: nesquena-hermes <agent@nesquena-hermes>
Co-authored-by: TomBanksAU <TomBanksAU@users.noreply.github.com>
