Fixes the reviewed gaps: keyboard-inaccessible delete controls (SessionRail,
Entities row), case-sensitive entity filter, two competing entity-detail
navigation patterns (standardize on EntitySheet), non-clickable Overview KPI
cards, a bare button bypassing the shared Button component, inconsistent
blur-only vs live filtering, and an unenforced sanitization assumption on
search snippet HTML (now using the already-present dompurify dependency).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>