fix(onboarding): prefill verified email in a disabled field; bump SDK 0.2.4

- Onboarding reads the OAuth email (session-storage hint + live Supabase
  session via getUserEmail) so Continue is no longer disabled.
- Replace the empty 'Signed in as' banner with a disabled, prefilled
  email field (email is fixed — Google-verified).
- Stash the verified email at OAuth callback time for onboarding prefill.
- Bump @abe-kap/appshell-sdk to ^0.2.4 (getUserEmail via getSession).

package.json

@@ -9,7 +9,7 @@
     "lint": "eslint"
   },
   "dependencies": {
-    "@abe-kap/appshell-sdk": "^0.2.3",
+    "@abe-kap/appshell-sdk": "^0.2.4",
     "clsx": "^2.1.1",
     "lucide-react": "^1.21.0",
     "next": "16.2.9",