Cardano Updates

Implements a fallback path that redeems subsequent NIGHT token thaws
directly from the Cardano blockchain when the Midnight API is unavailable.

- Add escrow module: discovery, datum parsing, address derivation, tx building
- Fix discovery.ts to handle API response shape (JSON plutus_data, not CBOR hex)
- Add null safety to datum parser integer fields
- Extend transaction builder with script inputs, reference inputs, collateral,
  validity intervals, and inline datum support
- Add ESCROW_REDEEM.md documenting the full flow

- Add new physical Cardano card image asset
- Update title to 'Physical Cardano Card Now Available'
- Update description to 'Limited stock — secure yours now and start spending in the real world.'
- Remove duplicate heading from modal content
- Add top padding for better spacing
- Change storage keys to reset announcement for all users

- Change initial route from HomeScreen to VotingOptionsScreen
- Update title from "Governance Dashboard" to "Governance"
- Update subtitle to "You can pick a DRep using their ID, choose to abstain or show no confidence."
- Update navigateToGovernanceCentre() to navigate to voting options
- Add analytics tracking for staking-gov-voting-options route

Co-authored-by: Cerkoryn <[email protected]>
Co-authored-by: Rahul <[email protected]>