fix: -repair uses node:sqlite, not better-sqlite3

better-sqlite3 is not a project dependency — the daemon uses node:sqlite
(built-in) via mailx-store. -repair was crashing with ERR_MODULE_NOT_FOUND
on first run. Swap the dynamic import to node:sqlite's DatabaseSync, and
move the WAL setting from .pragma() (better-sqlite3-specific) to
.exec("PRAGMA …") (works on both).
