Topics list: highlight newly active/resurfaced topics

[AndreRobitaille]

Summary

Add lightweight visual indicators for newly active, resurfaced, or high-importance Topics.

Requirements

• Signals are structural (recurrence, deferral, return after dormancy).
• Avoid rhetorical or sentiment-based emphasis.

Acceptance criteria

• Highlights draw attention to continuity shifts without editorializing.

[AndreRobitaille]

Implementation Complete

Added lightweight structural highlight indicators to the Topics index.

What changed

• Controller (topics_controller.rb): Queries TopicStatusEvent records from the last 30 days to build a @highlight_signals hash. Also fixed a pre-existing bug where show was defined below private, preventing the topic detail page from loading.
• Helper (topics_helper.rb): Added highlight_signal_label mapping event types to resident-facing labels.
• View (topics/index.html.erb): Topic cards now show lifecycle badges (Active/Dormant/Resolved/Recurring) and, when a recent continuity shift exists, a left-border accent plus signal badges.
• CSS (application.css): Added .card--highlighted, .card-signals, .badge--outline, .badge--info, .badge--secondary.
• Tests: 5 new controller tests covering lifecycle badges, signal rendering, no-signal baseline, deferral signals, and 30-day window expiry.

Signal types surfaced

Event	Label
agenda_recurrence	Resurfaced
deferral_signal	Deferral Observed
cross_body_progression	Moved Bodies
disappearance_signal	Disappeared
rules_engine_update → active	Newly Active

All signals are structural per Topic Governance — no rhetorical or sentiment-based emphasis.