Cascade v0.2.1-android (Android)

android: fix sign-in (INTERNET permission) + scrollable layout; v0.2.1

Two fixes from on-device testing of 0.2.0:

- Add the INTERNET permission. Cascade was an offline app (bundled audio), so
  it was never declared — and the account/sync feature is the first code that
  makes an HTTP call, so every request threw ("Couldn't send the sign-in link").
- Make the main screen vertically scrollable and drop the weight-based spacer
  (incompatible with scrolling). Content was overflowing the viewport with no
  scroll, clipping the custom-timer input field into a stray box overlapping the
  sleep-timer chips. Also moved the sign-in/account box below the timer controls.

Bumps to 0.2.1 / versionCode 3.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>