UME: renew token when expires_in is 0; token UI loading + toasts; sync thread status hint

- keepalive: call renew when has_token and (expires_in<=0 or below renew_before) so 0s stuck state self-heals\n- alarms/inventory auto loops: set last_error while pulling so table is not stuck at init with no hint\n- UmePage: warn pills for connected+需续期, spinners on token actions, toast ok/err from App, invalidate sync status after token ops

Co-authored-by: Cursor <cursoragent@cursor.com>

web/src/App.tsx

@@ -335,7 +335,7 @@ function App() {
               />
             }
           />
-          <Route path="/ume" element={<UmePage />} />
+          <Route path="/ume" element={<UmePage toastOk={showOk} toastError={showError} />} />
         </Routes>
         {toast && <div className={`toast toast--${toast.type}`}>{toast.text}</div>}
     </AppLayout>