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

packages/ui/primitives/document-flow/add-fields.tsx

@@ -508,7 +508,15 @@ export const AddFieldsFormPartial = ({
   }, []);
 
   useEffect(() => {
-    setSelectedSigner(recipients.find((r) => r.sendStatus !== SendStatus.SENT) ?? recipients[0]);
+    const recipientsByRoleToDisplay = recipients.filter(
+      (recipient) =>
+        recipient.role !== RecipientRole.CC && recipient.role !== RecipientRole.ASSISTANT,
+    );
+
+    setSelectedSigner(
+      recipientsByRoleToDisplay.find((r) => r.sendStatus !== SendStatus.SENT) ??
+        recipientsByRoleToDisplay[0],
+    );
   }, [recipients]);
 
   const recipientsByRole = useMemo(() => {
@@ -517,6 +525,7 @@ export const AddFieldsFormPartial = ({
       VIEWER: [],
       SIGNER: [],
       APPROVER: [],
+      ASSISTANT: [],
     };
 
     recipients.forEach((recipient) => {
@@ -529,7 +538,12 @@ export const AddFieldsFormPartial = ({
   const recipientsByRoleToDisplay = useMemo(() => {
     // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
     return (Object.entries(recipientsByRole) as [RecipientRole, Recipient[]][])
-      .filter(([role]) => role !== RecipientRole.CC && role !== RecipientRole.VIEWER)
+      .filter(
+        ([role]) =>
+          role !== RecipientRole.CC &&
+          role !== RecipientRole.VIEWER &&
+          role !== RecipientRole.ASSISTANT,
+      )
       .map(
         ([role, roleRecipients]) =>
           // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
@@ -544,12 +558,6 @@ export const AddFieldsFormPartial = ({
       );
   }, [recipientsByRole]);
 
-  const isTypedSignatureEnabled = form.watch('typedSignatureEnabled');
-
-  const handleTypedSignatureChange = (value: boolean) => {
-    form.setValue('typedSignatureEnabled', value, { shouldDirty: true });
-  };
-
   const handleAdvancedSettings = () => {
     setShowAdvancedSettings((prev) => !prev);
   };
@@ -687,9 +695,7 @@ export const AddFieldsFormPartial = ({
                       )}
 
                       {!selectedSigner?.email && (
-                        <span className="gradie flex-1 truncate text-left">
-                          {selectedSigner?.email}
-                        </span>
+                        <span className="flex-1 truncate text-left">{selectedSigner?.email}</span>
                       )}
 
                       <ChevronsUpDown className="ml-2 h-4 w-4" />