Fix two things live testing on 0.15.5 turned up

**About said "not detected".** Generation was only worked out from the reply to
a registry method, which we never send to a server that does not advertise
urn:stalwart:jmap — every 0.16 build does, and nothing older knows the
capability at all, so its absence is already the answer. Say so, instead of
shrugging. A session with no capabilities at all stays unknown, which is a
different thing from old.

**The caret jumped out of the OTP field after one digit.** Dialog's autofocus
effect listed onClose in its dependencies, and every caller passes an inline
arrow, so each keystroke in a dialog holding state tore the effect down, set it
up again, and refocused the first field — which in the disable-2FA dialog is
the password. Keep the handler in a ref so the effect depends only on `open`.
This was a bug in the shared dialog rather than in one screen; every dialog
with more than one field had it.

The test for it fails against the old dependency array, not just passes
against the new one.

web/src/ui/dialog.tsx

@@ -16,13 +16,23 @@ interface DialogProps {
 
 export function Dialog({ open, onClose, title, children, footer, size = "md", closeOnBackdrop = true, className }: DialogProps) {
   const ref = useRef<HTMLDivElement>(null);
+  /*
+   * Callers almost always pass an inline arrow for onClose, so its identity
+   * changes on every render of the parent. Depending on it here would tear the
+   * effect down and set it up again on every keystroke in a dialog that holds
+   * state, and the autofocus below would drag the caret back to the first
+   * field mid-typing. Keep the latest handler in a ref instead, so the effect
+   * depends only on `open`.
+   */
+  const onCloseRef = useRef(onClose);
+  onCloseRef.current = onClose;
   useEffect(() => {
     if (!open) return;
     const prev = document.activeElement as HTMLElement | null;
     const onKey = (e: KeyboardEvent) => {
       if (e.key === "Escape") {
         e.stopPropagation();
-        onClose();
+        onCloseRef.current();
       }
       if (e.key === "Tab" && ref.current) {
         const focusables = ref.current.querySelectorAll<HTMLElement>('button,[href],input,select,textarea,[tabindex]:not([tabindex="-1"]),[contenteditable="true"]');
@@ -48,7 +58,7 @@ export function Dialog({ open, onClose, title, children, footer, size = "md", cl
       document.removeEventListener("keydown", onKey, true);
       prev?.focus?.();
     };
-  }, [open, onClose]);
+  }, [open]);
   if (!open) return null;
   return createPortal(
     <div