~x-ai/grok-latest → A (2:1)

A fixes real indexing inconsistency (1-based/unwrap_or(0) → 0-based expect aligned with /t/tag/N), updating RPC, types, HTML links, and integration asserts so rank-history URLs are correct. B only regroups unranked siblings into singleton nav groups plus a unit test—a narrower UI presentation tweak with less cross-cutting impact.