fix(lint): fix 2 CI errors — missing test import and eqeqeq violation

[OAKVISUALZ]

Closes #506

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Summary

Fixes two ESLint errors (exit code 1) in the backend CI �ackend-checks job. These are not related to any open feature issue — they are standalone lint regressions in main.

Error 1 — \sorobanService.test.js:310:1\ — Parsing error: Unexpected token

The file uses bare \ est()\ calls (lines 258–309) but \ est\ was never imported from
ode:test. Only { describe, it, beforeEach, afterEach }\ were imported. ESLint's parser treated \ est\ as an unknown global and threw a parse error.

Fix: Added \ est\ to the destructured import on line 13.

Error 2 — \userDashboardService.js:227:21\ — Expected '===' and instead saw '==' (eqeqeq)

\\js
// Before
const str = value == null ? '' : String(value);
// After
const str = (value === null || value === undefined) ? '' : String(value);
\\

Both fixes are semantically equivalent — the behaviour does not change.

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Note: The remaining 55 items in the CI output are warnings only — they do not cause the exit code 1 failure and are out of scope for this PR.