fix: show save button when creating a new role (#17163)

## Summary
Fixes a regression where the save button was not visible when creating a
new role.

## Root Cause
PR #17062 (RLS FE implementation) introduced a change to the `isDirty`
logic that added `isDefined(settingsPersistedRole)` as a condition:

```typescript
const isDirty =
  isDefined(settingsPersistedRole) &&
  !isDeeplyEqual(settingsDraftRole, settingsPersistedRole);
```

However, in create mode, `settingsPersistedRole` is intentionally set to
`undefined` (in `SettingsRoleCreateEffect.tsx`), causing `isDirty` to
always evaluate to `false` and hiding the save button.

## Fix
Added `isCreateMode` to the `isDirty` condition so the save button shows
when creating a new role:

```typescript
const isDirty =
  isCreateMode ||
  (isDefined(settingsPersistedRole) &&
    !isDeeplyEqual(settingsDraftRole, settingsPersistedRole));
```

cc @Weiko

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Restores save button visibility when creating a role.
> 
> - Simplifies `isDirty` to `!isDeeplyEqual(settingsDraftRole,
settingsPersistedRole)`, removing the `isDefined(settingsPersistedRole)`
check so create-mode is considered dirty.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
21593d54c373b15b09406502f8d931cb5e203e46. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: Weiko <corentin@twenty.com>

packages/twenty-front/src/modules/settings/roles/role/components/SettingsRole.tsx

@@ -87,9 +87,7 @@ export const SettingsRole = ({ roleId, isCreateMode }: SettingsRoleProps) => {
     },
   ];
 
-  const isDirty =
-    isDefined(settingsPersistedRole) &&
-    !isDeeplyEqual(settingsDraftRole, settingsPersistedRole);
+  const isDirty = !isDeeplyEqual(settingsDraftRole, settingsPersistedRole);
 
   const handleCancel = () => {
     if (isCreateMode) {