Transfer to Spending from HW device flow

[ovitrif]

Part of #998.

Scope

Implement the watch-only hardware-wallet Transfer to Spending flow. Channel funding is a send signed on the Trezor device.

Flow:

• Amount step:
  • numpad
  • AVAILABLE = savings limit
  • 25% shortcut
  • MAX = savings - fees/reserve, or the Blocktank limit
  • over-max resets and shows error toast
• Review & Sign:
  • SIGN WITH YOUR DEVICE
  • network/service fees
  • to-spending amount
  • total
  • Open Trezor Connect
  • disconnected state shows Reconnect Hardware Device error
• Transaction Signed:
  • checkmark
  • auto-forwards after a short delay
• Processing Payment:
  • existing frame

Figma: https://www.figma.com/design/ltqvnKiejWj0JQiqtDf2JJ/Bitkit-Wallet?node-id=45010-105357