test(e2e): cover full Send Money wizard to receipt

[yunus-dev-codecrafter]

closes #464

Summary

Adds end-to-end Playwright test coverage for the Send Money wizard flow, ensuring users can successfully navigate from recipient address entry through amount selection, review, and confirmation to the transaction receipt.

Changes

• Created tests/e2e/send-flow.spec.ts with comprehensive test coverage
• Tests all three wizard steps: recipient → amount → review → receipt
• Validates address gating (Continue button disabled until checksum-valid Stellar key)
• Asserts progress indicator transitions (1 → 2 → 3)
• Tests back navigation between steps
• Validates amount constraints (min $1, max $10,000)
• Verifies currency selection persistence through flow
• Confirms receipt displays correct transaction details

Testing

Uses role/label-based selectors (getByRole, getByLabel) following existing e2e conventions. Tests cover:

• Address validation with invalid/valid transitions
• Recent recipients quick-fill
• Complete wizard path to receipt
• Edge cases (back navigation, amount limits)

Acceptance Criteria

✅ Full wizard path covered
✅ Address gating asserted
✅ Receipt assertion on confirm
✅ Role/label-based selectors