feat: cover all error paths

[naftalimurgor]

Summary

• Cover all error paths for submitted transaction statuses

[Sikkra]

Opened PR #38 for this: #38

It covers submitted WBGL transaction error paths that could otherwise keep conversions pending indefinitely:

• sendWBGL() now rejects when sendSignedTransaction emits an error.
• failed on-chain receipts are marked error.
• missing submitted receipts expire after configurable one-minute checks via PENDING_TX_MAX_CHECKS.

Verification:

• node --check on modified service files
• npx mocha src/tests/transactionStatus.js --timeout 10000 in service/ (4 passing)
• git diff --check

USDT-TRC20 payout address if accepted: TPwPFww7zxXFQ7zugo22gktQhckWVarRqi