Mail: instant first paint from the last saved accounts, folders and list; Outlook folders in one batched call; gzip for app files and large mail responses

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

public/settings.js

@@ -170,6 +170,6 @@ function viewSettings() {
       el.querySelector('#sx').onclick = closeSheet;
     } catch (e) { toast(e.message); }
   };
-  $('#hubout').onclick = async () => { await authPost('/api/auth/logout'); location.replace('/login'); };
+  $('#hubout').onclick = async () => { try { mcClear(); for (const k of Object.keys(localStorage)) if (k.startsWith('dc:')) localStorage.removeItem(k); } catch {} await authPost('/api/auth/logout'); location.replace('/login'); };
   const out = $('#out'); if (out) out.onclick = () => { store.del('sf_token'); toast('Signed out'); viewSettings(); };
 }