test(unit): add InvoiceRepository and UserRepository unit tests

[CKodidela]

Description

Add unit tests for InvoiceRepository and UserRepository — two data-access layer components that had ~21% statement
coverage and 0% branch coverage. All public methods are now covered using a sinon-stubbed DB client with no real
database connections.

Related Issue

Closes #491

Motivation and Context

Both repositories lacked meaningful test coverage, making regressions in DB query logic hard to catch. These tests
cover all public CRUD methods and edge cases (missing rows, error propagation, default values, query structure).

How Has This Been Tested?

• 20 new tests for InvoiceRepository under test/unit/repositories/invoice-repository.spec.ts
• 21 new tests for UserRepository under test/unit/repositories/user-repository.spec.ts
• Full test suite (1002 tests) passes with no regressions
• DB client stubbed via sinon throughout — no real DB connections used

Coverage after this PR:

File	Statements	Branches
invoice-repository.ts	21% → 88%	0% → 44%
user-repository.ts	21% → 93%	0% → 67%

Types of changes

• Non-functional change (docs, style, minor refactor)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my code changes.
• I added a changeset, or this is docs-only and I added an empty changeset.
• All new and existing tests passed.

[Copilot]

Pull request overview

Adds unit test coverage for two previously under-tested data-access repositories (InvoiceRepository, UserRepository) by stubbing the DB client and asserting query behavior without real database connections.

Changes:

• Add UserRepository unit tests covering lookups, upserts, vanish-state hydration, balance reads, and stored-procedure calls.
• Add InvoiceRepository unit tests covering stored-procedure confirmation, retrieval, pending-invoice paging, status updates, and upserts.
• Add a changeset entry documenting the test-only change.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
test/unit/repositories/user-repository.spec.ts	New unit tests for UserRepository methods and query behavior using sinon-stubbed DB client.
test/unit/repositories/invoice-repository.spec.ts	New unit tests for InvoiceRepository methods, including stored procedures and SQL generation.
.changeset/invoice-user-repo-unit-tests.md	Changeset noting the added unit tests.

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[Copilot]

This test claims to verify that pubkey is encoded as a hex buffer, but it only asserts the SQL contains the hex substring. That would still pass if pubkey were inserted as a plain string. Consider asserting for the specific Postgres buffer literal format Knex generates (e.g., X'…' / E'\\x…') to make the test actually validate the encoding.

Suggested change

	expect(sql).to.include(pubkeyHex)
	expect(sql).to.match(new RegExp(`(?:X'${pubkeyHex}'|E'\\\\\\\\x${pubkeyHex}')`, 'i'))

[CKodidela]

updated

[coveralls]

coverage: 74.365% (+0.6%) from 73.743% — CKodidela:test/invoice-user-repos into cameri:main