fix: address code review feedback on network attention display
- Clamp ScoreDetail percentage to max 99 so engaged talks never show 100%
- Distinguish real HTTP errors (429, 5xx) from expected 401/504 in useCrawlData
- Replace O(n²) talks.find with Map lookup in ScoredTalksGrid memo
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>