test(sdk): XDR roundtrip tests for transaction builder helpers

[blockchain-maxis]

Summary

• Adds sdk/tests/xdr-roundtrip.test.ts with 6 tests covering every transaction builder helper in sdk/src/claimableBalance.ts
• Tests encode → decode → assert deep equality on the operations array for:
  • createEscrow → Operation.createClaimableBalance (native XLM + non-native asset variants)
  • claimEscrow → Operation.claimClaimableBalance
  • reclaimEscrow → Operation.claimClaimableBalance
  • Full envelope stability (tx.toXDR() → fromXDR() → toXDR() is idempotent)
• Uses the real @stellar/stellar-sdk — no mocking of TransactionBuilder or operations
• Uses hardcoded valid Stellar public keys to avoid crypto.getRandomValues issues in jsdom

closes #257

Test results

PASS tests/xdr-roundtrip.test.ts
  XDR roundtrip — createEscrow (createClaimableBalance)
    ✓ operations survive encode → decode unchanged
    ✓ non-native asset roundtrips without data loss
  XDR roundtrip — claimEscrow (claimClaimableBalance)
    ✓ operations survive encode → decode unchanged
  XDR roundtrip — reclaimEscrow (claimClaimableBalance by sender after deadline)
    ✓ operations survive encode → decode unchanged
  XDR envelope stability
    ✓ re-encoding the decoded TX produces the same XDR (full envelope roundtrip)
    ✓ claimClaimableBalance re-encoding is stable

Tests: 6 passed, 6 total

[vercel]

@blockchain-maxis is attempting to deploy a commit to the miracle656's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@blockchain-maxis Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits