feat: update SDK with batched methods + 27 unit tests

SDK updates:
- postTask: batched init+delegate (1 tx instead of 2)
- stakeAndProve: batched lockStake+submitProof (1 tx)
- settleAndArchive: batched settleJob+archiveSettlement (1 tx)
- archiveSettlement: standalone archive method
- compressFinishedJob: ZK compression method

Tests (27 passing):
- constructor, postTask batching, bid, lockStake, stakeAndProve
- submitProof, settle, settleAndArchive, compressFinishedJob
- storeCredential, encrypt/decrypt roundtrip, getBalance
- airdrop, searchTasks, getTask, deadline parsing

Author: jimmdd