fix(auth): add account, session, and verification schemas; make passwordHash nullable

Backend/public/mobile-sim.js

@@ -127,7 +127,13 @@
         const payload = await response.json().catch(() => ({}));
 
         if (!response.ok) {
-          throw new Error(payload.message || response.statusText);
+          const errorMessage =
+            payload?.message ||
+            payload?.error?.message ||
+            payload?.error ||
+            payload?.code ||
+            `${response.status} ${response.statusText}`;
+          throw new Error(errorMessage);
         }
 
         return payload;