feat(wasm-solana): add SPL Stake Pool instruction decoding for Jito

Add support for decoding SPL Stake Pool instructions used by Jito
liquid staking. This enables WASM-based parsing of Jito staking
transactions for parity with BitGoJS.

Changes:
- Add spl-stake-pool dependency for official Borsh deserialization
- Add STAKE_POOL_PROGRAM_ID constant for SPoo1Ku8WFXoNDMHPsrGSTSG1Y47rzgn41SLUNakuHy
- Add StakePoolDepositSol and StakePoolWithdrawStake instruction types
- Add decode_stake_pool_instruction using official StakePoolInstruction enum
- Add TypeScript interfaces for stake pool instructions
- Add Jito transaction parsing tests using BitGoJS test fixtures

Ticket: BTC-2932

Author: lcovar