Raw-IndexedDB cache (lotus-search-cache: messages keyed [roomId,eventId] +
per-room coverage) merged into local search with in-memory-wins dedupe. OPT-IN
(default off) via a standalone atom — stores decrypted text at rest, so it ships
with a privacy note, a Clear button, and an unconditional wipe on logout
(initMatrix). All IDB errors degrade to cache-miss. +8 tests (1 IDB skip in node).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
