fix(tests): scope the sync_queue cleanup wipe to the test devices

The cleanup in setupSyncTestDB ran DELETE FROM sync_queue WHERE true —
a table-wide wipe that discards REAL devices' pending offline entries
on every suite run. Same class as the 2026-10-14 reading_history
incident the standing rules ban. The test's own queue items cascade
from its 'Test %'-named device, so the wipe is redundant for cleanup —
scoped it to those devices (defense in depth ahead of the cascade).

Flagged during H1 verification: the line executed during an in-
container suite run this session; any device with pending offline
queue entries at that moment should re-push on its next sync.

cmd/server/tests/sync_integration_test.go

@@ -37,7 +37,10 @@ func setupSyncTestDB(t *testing.T) *database.Queries {
 		// here silently destroyed a live reader's stats data on every
 		// suite run (2026-10-14). Sync-test sessions belong to the
 		// test-sync users; deleting those users cascades their rows.
-		_, _ = dbPool.Exec(ctx, "DELETE FROM sync_queue WHERE true")
+		// Same rule for sync_queue: a `WHERE true` wipe could discard a
+		// REAL device's pending offline entries — scope to the test
+		// devices (their cascade covers the rest).
+		_, _ = dbPool.Exec(ctx, "DELETE FROM sync_queue WHERE device_id IN (SELECT id FROM devices WHERE device_name LIKE 'Test %')")
 		_, _ = dbPool.Exec(ctx, "DELETE FROM users WHERE email LIKE 'test-sync%'")
 		_, _ = dbPool.Exec(ctx, "DELETE FROM media_items WHERE title LIKE 'Test %'")
 		_, _ = dbPool.Exec(ctx, "DELETE FROM libraries WHERE name LIKE 'Test %'")