fix(ui): discard cancelled signature pad dialog drafts

The dialog kept its draft signature in state across open/close, while
the pad inside remounts from the saved value. After cancelling,
reopening showed the saved signature (or an empty pad), but the Next
button stayed enabled and committed the discarded draft.

Reset the draft to the saved value whenever the dialog opens or closes,
and route all open-state changes through one disabled-aware handler.

packages/ui/primitives/signature-pad/signature-pad-dialog.tsx

@@ -41,6 +41,15 @@ export const SignaturePadDialog = ({
   const [showSignatureModal, setShowSignatureModal] = useState(false);
   const [signature, setSignature] = useState<string>(value ?? '');
 
+  const onOpenChange = (open: boolean) => {
+    if (disabled) {
+      return;
+    }
+
+    setSignature(value ?? '');
+    setShowSignatureModal(open);
+  };
+
   return (
     <div
       className={cn(
@@ -62,7 +71,7 @@ export const SignaturePadDialog = ({
         type="button"
         disabled={disabled}
         className="absolute inset-0 flex items-center justify-center bg-transparent"
-        onClick={() => setShowSignatureModal(true)}
+        onClick={() => onOpenChange(true)}
         whileHover="onHover"
       >
         {!value && !disableAnimation && (
@@ -109,7 +118,7 @@ export const SignaturePadDialog = ({
         )}
       </motion.button>
 
-      <Dialog open={showSignatureModal} onOpenChange={disabled ? undefined : setShowSignatureModal}>
+      <Dialog open={showSignatureModal} onOpenChange={onOpenChange}>
         <DialogContent hideClose={true} className="p-6 pt-4">
           <SignaturePad
             id="signature"
@@ -135,7 +144,7 @@ export const SignaturePadDialog = ({
               disabled={!signature}
               onClick={() => {
                 onChange(signature);
-                setShowSignatureModal(false);
+                onOpenChange(false);
               }}
             >
               {dialogConfirmText ? parseMessageDescriptor(i18n._, dialogConfirmText) : <Trans>Next</Trans>}