Cache eviction tests named LRU but implementation is FIFO

[pedrofuentes]

Sentinel finding #2 (SNT-9c84f03f)

\comment-thread-sync.ts:337-345\ — \�victIfNeeded\ always removes the first-inserted key (FIFO). Tests describe it as 'LRU'. Either rename to FIFO or implement true LRU (delete+re-set on access).

Priority: 🟡 IMPORTANT