v2026.9.3.0

## What's Changed
* feat(image_proxy_service): migrate image proxy service to gateway by @whutchinson98 in https://github.com/macro-inc/macro/pull/6145
* fix(local): derive DCS FusionAuth OAuth redirect from instance port by @whutchinson98 in https://github.com/macro-inc/macro/pull/6153
* feat(new-layout): add new thin, big icon sidebar behind layout feature flag by @sedson in https://github.com/macro-inc/macro/pull/6149
* fix(channel/agent): extract magic chip message + id on all reply paths by @sedson in https://github.com/macro-inc/macro/pull/6157
* feat(agent_harness_service): migrate agent harness service to gateway by @whutchinson98 in https://github.com/macro-inc/macro/pull/6155
* fix(web): gate the inbox notified_at sort behind a PostHog flag by @gbirman in https://github.com/macro-inc/macro/pull/6158
* feat(new-layout): new channels view by @dev-rb in https://github.com/macro-inc/macro/pull/6146
* feat(web): better feature flag definition and use interface by @dev-rb in https://github.com/macro-inc/macro/pull/6102
* refactor(web): use new feature flag interface by @dev-rb in https://github.com/macro-inc/macro/pull/6104
* fix(fusionauth): carry granted scopes onto login-issued Google refresh tokens by @gbirman in https://github.com/macro-inc/macro/pull/6159
* perf(soup): linearize the notified-at candidate query by @gbirman in https://github.com/macro-inc/macro/pull/6162
* feat(calendar): overlay teammates out-of-office on the calendar by @gbirman in https://github.com/macro-inc/macro/pull/6156
* fix(inbox): show relative time for activity under a minute old by @gbirman in https://github.com/macro-inc/macro/pull/6164
* fix(calendar): dedupe occurrences and reap wedged Google backfills by @gbirman in https://github.com/macro-inc/macro/pull/6163
* feat(connection_gateway): migrate connection gateway to gateway by @whutchinson98 in https://github.com/macro-inc/macro/pull/6165
* feat(activity): attribute AI tool creates and edits to the tool actor (Macro AI) by @synoet in https://github.com/macro-inc/macro/pull/6050
* feat(agent_schedule_service): migrate agent schedule service to gateway by @whutchinson98 in https://github.com/macro-inc/macro/pull/6171
* fix(md): fix skeleton + error bug, improve error styling by @sedson in https://github.com/macro-inc/macro/pull/6169
* feat(new-layout): new tasks view by @dev-rb in https://github.com/macro-inc/macro/pull/6175
* fix(channels): delete channel endpoint broken by @whutchinson98 in https://github.com/macro-inc/macro/pull/6180
* fix(activity): attribute signup defaults and support channel to system by @synoet in https://github.com/macro-inc/macro/pull/6049
* feat(calendar): fold the calendar side list into per-account groups by @gbirman in https://github.com/macro-inc/macro/pull/6179
* feat(calendar): show one per-account toggle in the compact calendar pickers by @gbirman in https://github.com/macro-inc/macro/pull/6184
* chg(theme/ui): remove --lift token use layer context + offset prop by @sedson in https://github.com/macro-inc/macro/pull/6178
* feat(md): trailing/trapped paragraph plugin by @sedson in https://github.com/macro-inc/macro/pull/6186
* feat(calendar_events): create out-of-office events via event type by @gbirman in https://github.com/macro-inc/macro/pull/6183
* feat: custom Macro MCP via ACP -->  inferred tools by @404Wolf in https://github.com/macro-inc/macro/pull/6154
* fix(inbox): restore soup rows to done-filtered feeds on incoming notifications by @gbirman in https://github.com/macro-inc/macro/pull/6185
* fix(calendar): distinguish failed team OOO fetch from empty result by @gbirman in https://github.com/macro-inc/macro/pull/6182
* fix(channel): start typing from composer text changes by @synoet in https://github.com/macro-inc/macro/pull/6187
* fix(calendar): merge consecutive working-location events into one bar by @gbirman in https://github.com/macro-inc/macro/pull/6192
* chore(agents): model ui grouping by @404Wolf in https://github.com/macro-inc/macro/pull/6177
* fix(agent): render dollar-delimited math correctly by @404Wolf in https://github.com/macro-inc/macro/pull/5988


**Full Changelog**: https://github.com/macro-inc/macro/compare/v2026.9.2.0...v2026.9.3.0