Acknowledge Notice

"I have read this" on a Notices card (Today v4 data gap #1966).

⛔THE WRITE THE BUTTON NEVER HAD. TodayPage.tsx's old onAcknowledge only set local React state (setAcked) -- a refresh, or a second device, forgot it ever happened. This calls the real ledger (announcements.acknowledge, migration 0530, Track E15), on the web channel ACK_CHANNELS names for exactly this: acknowledging on the manager screen without Roost ever having sent on that channel.

Always the CALLING principal's own acknowledgement -- no principal_id parameter, same discipline as get_role_config above. acknowledged: false (never a 404/403) when the caller was not this announcement's recipient, or had already acknowledged it: acknowledge's own docstring calls that refusal "the positive control for the whole table", and this route is not the place to turn it into an error the caller has to specially handle for what is, from their side, already true either way.