feat(register): ask for date of birth and place of study

TODO.md

@@ -15,6 +15,8 @@ Remove items from this list once they are done.
   Sentry needs ProGuard keep rules
 - verify the SDK 58 upgrade on devices: an expiry reminder notification and an error that lands
   in Bugsink, on Android and an iOS EAS build
+- check the registration form's birth date wheel on iOS (`src/components/DateField.tsx`), only
+  tested on Android so far
 - verify the Stripe Checkout purchase flow end to end (needs galtinn deployed with
   `/api/stripe/checkout-session/app/` first): a test-mode purchase on Android and iOS with `4242…`,
   a card that requires 3D Secure and a cancel, checking the app lands back on the proof with the
@@ -26,10 +28,6 @@ Remove items from this list once they are done.
   endpoint and its `payment_intent.succeeded` handling
 - test in ios emulator? (`npm run ios`, requires macOS)
 - characters in the password input field are invisible
-- ask for date of birth and place of study when registering: galtinn now requires them on its web
-  sign-up and profile forms, but `/api/user/register/` still treats them as read-only, so users
-  registered in the app must fill them in before they can save their profile on the web. Needs
-  galtinn's register serializer to accept them first
 - use [Expo Application Services](https://expo.dev/eas) to build and submit app to stores
 - explore Expo features:
   - add an iOS 26 liquid glass icon: a `.icon` file made with Apple's Icon Composer,