Implements the payment flow UI for the Element X ADA wallet:
## Screens
- PaymentEntryScreen: Amount/recipient input with pre-filling from /pay command
- PaymentConfirmationScreen: Transaction details with fee estimation (FLAG_SECURE)
- PaymentProgressScreen: Submission status with polling for confirmation
## Features
- Biometric authentication before payment confirmation
- Matrix user detection with 'hasn't linked wallet' inline message
- CardanoScan explorer link for transaction viewing
- Testnet warning banner
- Insufficient funds detection
## Wire-up
- MessageComposerPresenter intercepts /pay commands
- SlashCommandParser integration for command detection
- Navigation to PaymentFlowNode on valid /pay command
- Snackbar error on parse errors
## Technical
- Circuit presenter pattern with Molecule/Turbine tests
- @PreviewsDayNight for all Composables
- Metro DI integration
- Fake implementations for testing
Includes PaymentEntryPresenterTest, PaymentConfirmationPresenterTest,
PaymentProgressPresenterTest with comprehensive coverage.
Kayos
39561e1aeb