fix: cover submitted WBGL transaction errors

[Sikkra]

Summary

Covers submitted WBGL transaction error paths that could leave conversions stuck in pending:

• reject sendWBGL() when sendSignedTransaction emits an error so callers can enter their existing return/error handling path
• mark mined failed receipts as error instead of treating every receipt as eventually successful
• expire long-missing submitted receipts after a configurable number of one-minute checks (PENDING_TX_MAX_CHECKS, default 180, 0 disables)
• add focused helper coverage for receipt failure and pending-expiry decisions

Verification

• node --check service/src/modules/chores.js service/src/modules/web3.js service/src/utils/config.js service/src/utils/transactionStatus.js service/src/tests/transactionStatus.js
• npx mocha src/tests/transactionStatus.js --timeout 10000 in service/ (4 passing)
• git diff --check

Note: npx eslint ... is not a useful verifier in the current repo because the existing ESLint setup fails to parse ES module import syntax before it reaches the actual changes.

Related: #21
Program reference: BitgesellOfficial/bitgesell#81

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