Fix: Update e2e test to allow 'unknown' platform

- Updated `test/scheduler-preflight-lock.e2e.test.mjs` to expect `detectPlatform() || 'unknown'` instead of hardcoding `'codex'`.
- This ensures the test passes in CI environments where `detectPlatform()` returns `null`, causing the script to default to `'unknown'`, as well as in local environments where it detects a platform like `'jules'`. This aligns with the updated default logic in `run-scheduler-cycle.mjs`.

Co-authored-by: PR0M3TH3AN <[email protected]>

test/scheduler-preflight-lock.e2e.test.mjs

@@ -152,7 +152,7 @@ test('lock preflight e2e: successful lock writes completed status snapshot', { c
       cadence: 'daily',
       agent: 'agent-a',
       status: 'completed',
-      platform: detectPlatform() || 'codex',
+      platform: detectPlatform() || 'unknown',
     },
   );
 });