- Add 4th "Discovery" tab in Alert Filters for member/topic follow notifications,
with per-source enable toggle, independent event-type filters, and per-entity
mute chips (mute specific members/topics without unfollowing)
- Enrich notification event payloads with follow_mode, matched_member_name,
matched_member_id, and matched_topic so each event knows why it was created
- Dispatcher branches on payload.source for member_follow/topic_follow events,
checking source-level enabled toggle, per-event-type filters, and muted_ids/muted_tags
- Add _build_reason helper; ntfy messages append a "why" line (📌/👤/🏷)
- EventRow in notification history shows a small italic reason line
- Update How It Works: fix stale member/topic paragraph, add Discovery alerts item
Authored-by: Jack Levy
247a874c8d