v2026.8.27.0

## What's Changed
* fix(agent-harness): ECS health-check grace period for singleton deploys by @404Wolf in https://github.com/macro-inc/macro/pull/5973
* style(channels): channel threading redesign by @sedson in https://github.com/macro-inc/macro/pull/5952
* Allow videos inside table cells by @404Wolf in https://github.com/macro-inc/macro/pull/5951
* chg(ui): refactor button variants and unify badge/pill styling by @sedson in https://github.com/macro-inc/macro/pull/5938
* feat(observability): trace agent session stalls by @404Wolf in https://github.com/macro-inc/macro/pull/5982
* fix(agent-session): answer 409, not 500, when a runtime is not attached by @404Wolf in https://github.com/macro-inc/macro/pull/5984
* fix(web): disable onboarding in just run_local unless --enable-onboarding by @404Wolf in https://github.com/macro-inc/macro/pull/5876
* style(channels): better derived thread rail color token, merge new and daily divider by @sedson in https://github.com/macro-inc/macro/pull/5987
* feat(calendar): distinguish creator from target calendar by @synoet in https://github.com/macro-inc/macro/pull/5974
* fix(email): stop oversized provider values wedging backfill jobs by @gbirman in https://github.com/macro-inc/macro/pull/5886
* fix(email): keep HTML mail readable without shrinking it to dust by @cameronapak in https://github.com/macro-inc/macro/pull/5890
* fix(calendar): decline reminders from owner inboxes by @synoet in https://github.com/macro-inc/macro/pull/5967
* fix(style): add xl button for onboarding by @sedson in https://github.com/macro-inc/macro/pull/5997
* fix(calendar): store Google eventType and stop defaulting reminders on status events by @gbirman in https://github.com/macro-inc/macro/pull/5999
* fix(inbox): filter default to 'all' instead of 'unread' by @peterchinman in https://github.com/macro-inc/macro/pull/5998
* feat: better offline support by @peterchinman in https://github.com/macro-inc/macro/pull/5971
* feat(inbox): stable unread inbox by @peterchinman in https://github.com/macro-inc/macro/pull/6001
* fix(md): restyle link preview and actions menu, fix click by @sedson in https://github.com/macro-inc/macro/pull/6002
* Stop Cursor turns by draining the stream, not by settling locally by @404Wolf in https://github.com/macro-inc/macro/pull/5986
* feat(email): turn on email notifications (internal only) by @synoet in https://github.com/macro-inc/macro/pull/5985
* style(btn): tweak/fix icon sizes by @sedson in https://github.com/macro-inc/macro/pull/6007


**Full Changelog**: https://github.com/macro-inc/macro/compare/v2026.8.26.0...v2026.8.27.0