Harden auth requests and backup endpoints

webapp/src/App.tsx

@@ -1167,7 +1167,6 @@ export default function App() {
       const key = await encryptSessionUserKeyForAuthRequest(session, authRequest);
       await respondToAuthRequest(authedFetch, authRequest.id, {
         key,
-        masterPasswordHash: null,
         deviceIdentifier: getCurrentDeviceIdentifier(),
         requestApproved: true,
       });

webapp/src/lib/api/auth-requests.ts

@@ -52,7 +52,6 @@ export async function respondToAuthRequest(
   requestId: string,
   payload: {
     key?: string | null;
-    masterPasswordHash?: string | null;
     deviceIdentifier: string;
     requestApproved: boolean;
   }