Topics index: filters (status, body, timeframe)

[AndreRobitaille]

Summary

Add Topic-centric filters to the Topics index.

Requirements

• Filters include lifecycle status, governing body scope, and activity window.
• Filter state persists across pagination and sorting.

Acceptance criteria

• Residents can narrow Topics by status and body context without losing continuity cues.

[AndreRobitaille]

Status update (2026-04-14): still open.

Current state of topics index (TopicsController#index):

• Search via ?q= works with pagination.
• Default view shows a 6-topic hero (impact ≥ 30d activity) plus paginated active-topics list, ordered by resident_impact_score DESC, last_activity_at DESC, id DESC.
• No lifecycle status / governing body / activity window filters exposed in the UI.

With the newspaper homepage + topic-page redesigns shipped, filters are a lower priority (homepage does most of the surfacing now). Leaving open as future work — filter UI + filter state preservation across pagination still want doing.