New transaction.get_interchain and block.get_interchain call the prime-node
/api/v1/{transaction,block}/{id}/interchain endpoints, returning an
InterchainTrace {block_id, validator_blocks, interchain_transactions}. Adds
VerificationBlock / InterchainTransaction / InterchainTrace dataclasses with
from_dict, exports them, and a from_dict test.
Synchronous Python SDK modeled on prime-sdk-go. Provides DC1-HMAC-SHA256
auth, dataclass models, and resource clients for system, transaction,
transaction-type, smart-contract, and block endpoints, plus a YAML
credentials loader.
