feat: assistant role (#1588)

## Description

Introduces the ability for users with the **Assistant** role to prefill
fields on behalf of other signers. Assistants can fill in various field
types such as text, checkboxes, dates, and more, streamlining the
document preparation process before it reaches the final signers.

https://github.com/user-attachments/assets/c1321578-47ec-405b-a70a-7d9578385895

apps/web/src/app/(signing)/sign/[token]/assistant/assistant-confirmation-dialog.tsx

@@ -0,0 +1,73 @@
+import { Trans } from '@lingui/macro';
+
+import { Button } from '@documenso/ui/primitives/button';
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from '@documenso/ui/primitives/dialog';
+
+import { SigningDisclosure } from '~/components/general/signing-disclosure';
+
+type ConfirmationDialogProps = {
+  isOpen: boolean;
+  onClose: () => void;
+  onConfirm: () => void;
+  hasUninsertedFields: boolean;
+  isSubmitting: boolean;
+};
+
+export function AssistantConfirmationDialog({
+  isOpen,
+  onClose,
+  onConfirm,
+  hasUninsertedFields,
+  isSubmitting,
+}: ConfirmationDialogProps) {
+  const onOpenChange = () => {
+    if (isSubmitting) {
+      return;
+    }
+
+    onClose();
+  };
+
+  return (
+    <Dialog open={isOpen} onOpenChange={onOpenChange}>
+      <DialogContent>
+        <DialogHeader>
+          <DialogTitle>
+            <Trans>Complete Document</Trans>
+          </DialogTitle>
+          <DialogDescription>
+            <Trans>
+              Are you sure you want to complete the document? This action cannot be undone. Please
+              ensure that you have completed prefilling all relevant fields before proceeding.
+            </Trans>
+          </DialogDescription>
+        </DialogHeader>
+
+        <div className="flex flex-col gap-4">
+          <SigningDisclosure />
+        </div>
+
+        <DialogFooter className="mt-4">
+          <Button variant="secondary" onClick={onClose} disabled={isSubmitting}>
+            Cancel
+          </Button>
+          <Button
+            variant={hasUninsertedFields ? 'destructive' : 'default'}
+            onClick={onConfirm}
+            disabled={isSubmitting}
+            loading={isSubmitting}
+          >
+            {isSubmitting ? 'Submitting...' : hasUninsertedFields ? 'Proceed' : 'Continue'}
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}