Stop dropping civic-integrity labels on in-network TimelineHome

[Pitchfork-and-Torch]

Bug

FosnrCivicIntegrityDropRule lives in TWEET_LABEL_DROPS, which is TIMELINE_HOME_SHARED_RULES. VFFilter hard-drops Action::Drop on both TimelineHome and TimelineHomeRecommendations.

A followed civic-integrity labeled post therefore vanishes from Following and from in-network For You. DoNotAmplify is already OON-only (DoNotAmplifyOonDropRule on TimelineHomeRecommendations). Civic integrity is the same "do not amplify" family, wired one table too high.

Hate / violent-speech / abuse stay on TimelineHome. This is not fail-open on missing labels and not the VF dual-role merge (PR 55 / 90).

Fix

Move FosnrCivicIntegrityDropRule onto OON_TWEET_LABEL_DROPS. TimelineHome allows. TimelineHomeRecommendations still Drops. Same twin as DoNotAmplify.

Proof

• Entry: tweet_rules TWEET_LABEL_DROPS / RuleEngine TimelineHome
• Sink: VFFilter Action::Drop
• Break: civic integrity shared Home drop table; DoNotAmplify is Recommendations-only
• Viewer effect: followed civic-labeled post disappears from Home; OON amplification still blocked
• Twin: DoNotAmplifyOonDropRule

Tests

• fosnr_civic_integrity_label_allows_in_network (fails on unmodified main)
• fosnr_civic_integrity_label_drops_oon
• registry wired names: civic off TimelineHome, on Recommendations after DNA
• unit tests added; cargo test cannot run in the public dump