feat(permissions): add reset to defaults button in permissions modals (#25931)

Adds a 'Reset to Defaults' button to both the Edit Default Permissions
modal and the Edit User Group permissions modal.

- Default permissions modal: resets to stock/env-var configuration
- User group modal: resets to current global default permissions

Backend: new GET /api/v1/users/default/permissions/defaults endpoint
that returns DEFAULT_USER_PERMISSIONS (env-var-based initial defaults).

src/lib/apis/users/index.ts

@@ -85,6 +85,33 @@ export const updateUserDefaultPermissions = async (token: string, permissions: o
 	return res;
 };
 
+export const getUserDefaultPermissionsDefaults = async (token: string) => {
+	let error = null;
+
+	const res = await fetch(`${WEBUI_API_BASE_URL}/users/default/permissions/defaults`, {
+		method: 'GET',
+		headers: {
+			'Content-Type': 'application/json',
+			Authorization: `Bearer ${token}`
+		}
+	})
+		.then(async (res) => {
+			if (!res.ok) throw await res.json();
+			return res.json();
+		})
+		.catch((err) => {
+			console.error(err);
+			error = err.detail;
+			return null;
+		});
+
+	if (error) {
+		throw error;
+	}
+
+	return res;
+};
+
 export const updateUserRole = async (token: string, id: string, role: string) => {
 	let error = null;