Locks in the "pre-auth DB entry point defers while the encrypted cache is locked"
invariant that had zero coverage (which is how the PruneWorker/BackfillWorker gap
in #224 slipped in). Adds SyncWorkerTest and SendWorkerTest (locked -> retry with
the Lazy DB deps never resolved; unlocked -> runs), and a DatabaseProvisionerTest
case proving prepareCache() suspends on an auth-bound resolvePassphrase until it
resolves.
IdleService shares the same guard but is an Android Service (its start path needs
startForeground/Context), so its gate is covered by the instrumented test (#226)
rather than a JVM unit test.
Closes#225
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
JMR-devandClaude Opus 4.8
6d75bf5c6d