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/index.css

@@ -268,6 +268,29 @@ pre {
   border-color: #5f1f2a;
 }
 
+.inline-spinner {
+  display: inline-block;
+  width: 14px;
+  height: 14px;
+  margin-right: 8px;
+  border: 2px solid rgba(255, 255, 255, 0.22);
+  border-top-color: rgba(255, 255, 255, 0.85);
+  border-radius: 50%;
+  vertical-align: -2px;
+  animation: inline-spin 0.65s linear infinite;
+}
+
+@keyframes inline-spin {
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+.conn-pill--warn {
+  border-color: #664813;
+  color: #e7c46d;
+}
+
 .skeleton-line {
   height: 32px;
   border-radius: 8px;