Undismiss Activity

Remove a dismissal — activity reappears in feed and signals are cleared.

2026-05-23 — Delegated to the canonical services.activity_feedback restore_activity service. Previously this handler only cleared notification_dismissals + activity_signals — it left vibe_dismissals

• hard_exclusions in place. That meant a user who had downvoted via the Home/vibe path couldn't actually un-downvote: the activity stayed hidden from /api/discover/vibe and the ranker still treated it as a hard exclusion. The shared service now clears every table the downvote could have written to so restore is symmetric with record_activity_downvote.