Add Simulation/Live toggle to escrow page.
- Simulation (default): existing off-chain flow via backend API
- Live: same off-chain API but escrow detail shows 'View on Ledger' link and read-only ContractService data
Joey: toggle UI + mode state. Ralph: wire on-chain branch to ContractService.
Add Simulation/Live toggle to escrow page.
Joey: toggle UI + mode state. Ralph: wire on-chain branch to ContractService.