Complete the documentation suite with: - Deep-dive metrics reference (LCP, FCP, CLS, TBT, TTFB) - Detailed testing engines comparison (Sitespeed vs PSI) - Why TBT is the killer metric for rds.ink - How to fix each metric using Hummingbird - Score differences and when to use each engine Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>