Reservation CLI: SDK, CLI, and mock program

[martinsander00]

Split implementation of the reservation CLI tooling.

Tasks

• SDK: instruction builders, PDA helpers, raw-byte account parsers (DeviceHistory, MetroHistory, ClientSeat, PaymentEscrow)
• CLI: reservation subcommand (initialize-seat, withdraw, list, price) behind experimental feature gate

Context

• price command fetches MetroHistory + DeviceHistory via getProgramAccounts, joins client-side, displays base price + device premium
• All commands are behind the experimental feature gate
• Mock program mirrors the real on-chain program's account layouts for realistic integration testing