fix(card): make balance and card number visibility independent

Makes the balance and the card number visibility independent on the card detail screen, each behind its own eye icon.

Bug: https://hola-tech.sg.larksuite.com/record/QcPprUvObeCaGAcjlsglWM9agjh

Before

• The balance eye only toggled the balance; the card number was always exposed.

After

• The header eye toggles ONLY the card number on the preview (Show/Hide card number).
• The balance eye inside CardBalance self-manages its own visibility (uncontrolled).
• Toggling one never reveals or hides the other.

Files

• detail-card/[id].tsx: header eye drives isCardNumberVisible only; CardBalance is uncontrolled.
• card-vertical-simple.tsx: isVisible prop masks the card number when false.
• card-preview.tsx: forwards isVisible.
• card-balance.test.tsx: adds an uncontrolled/self-managed visibility test.

Testing

• Unit tests: 11/11 passed (card-vertical-simple + card-balance, incl. the new uncontrolled case).
• E2E speedrun on iOS (Xcode sim) and Android (emulator API 35) against an isolated local backend with an ACTIVE card:
  • Initial: balance ****** and card number •••• •••• both masked.
  • Show card number → only the card number reveals (•••• 1234); balance stays ******.
  • Show balance → only the balance reveals (1,000.00); card number unchanged.
  • Hide card number → only the card number masks; balance stays revealed.