Deflake the collab restore-listener DB test (poll for the PRE_RESTORE row)

The client converges on the restored content via the broadcast INSIDE the
document transact — before the listener commits the PRE_RESTORE version
row. Asserting the row immediately after convergence is a race that CI
lost on the #104 run; poll for it instead.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwZ4jR4KFAPvpjWevfUGX1

apps/collab/src/restore-listener.db.test.ts

@@ -141,12 +141,21 @@ describe.skipIf(!url)('restore listener (DB-backed, issue #42)', () => {
     expect(textOf(doc)).not.toContain('current text');
 
     // A pre-restore snapshot was appended; history is append-only (the original
-    // manual version is still present too).
+    // manual version is still present too). Poll: the broadcast the client
+    // converged on happens inside the transact, BEFORE the listener commits
+    // the PRE_RESTORE row — asserting immediately is a race.
+    const triggersNow = async (): Promise<string[]> => {
       const versions = await pool.query<{ trigger: string }>(
         'SELECT trigger FROM page_versions WHERE page_id = $1',
         [pageId],
       );
-    const triggers = versions.rows.map((r) => r.trigger);
+      return versions.rows.map((r) => r.trigger);
+    };
+    let triggers: string[] = [];
+    await waitFor(() => {
+      void triggersNow().then((rows) => (triggers = rows));
+      return triggers.includes('PRE_RESTORE');
+    });
     expect(triggers).toContain('PRE_RESTORE');
     expect(triggers).toContain('MANUAL');