test(domain): add reimbursements logic unit tests

[LogenNineFingersIsAlive]

Summary

Phase 2 (part 1) of domain testability: extract and unit-test reimbursements business logic.

What changed

• Added new pure logic module:
  • packages/domain/src/services/reimbursements-logic.ts
• Added unit tests:
  • packages/domain/src/services/__tests__/reimbursements-logic.test.ts
• Refactored reimbursements.service.ts to consume extracted pure helpers (no behavior changes intended)

Covered logic

• Positive minor validation
• Recoverable amount computation
• Reimbursement status derivation (none, expected, partial, settled, written_off)
• Outbound reimbursable assertions
• Inbound target/currency/amount link validations
• Close/write-off amount validations
• Category rule kind validations
• Auto-match helpers:
  • recovery window inclusion
  • allocation amount calculation

Validation

• pnpm --filter @tithe/domain typecheck
• pnpm --filter @tithe/domain test:coverage
• pnpm lint

Results:

• 131 domain unit tests passing (expenses + reimbursements logic suites)
• reimbursements-logic.ts at 100% statement/branch/function/line coverage

[Copilot]

Pull request overview

This PR improves domain-layer testability by extracting reimbursement business rules from reimbursements.service.ts into a pure logic module and adding a dedicated unit test suite, while keeping service behavior unchanged.

Changes:

• Added reimbursements-logic.ts containing pure validation/derivation helpers used by the reimbursements service.
• Refactored reimbursements.service.ts to delegate to the extracted helpers.
• Added reimbursements-logic.test.ts unit tests covering reimbursement logic paths.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
packages/domain/src/services/reimbursements.service.ts	Refactors service to call extracted pure helpers (validation, status derivation, auto-match helpers).
packages/domain/src/services/reimbursements-logic.ts	New pure business-logic module for reimbursements, intended for unit testing.
packages/domain/src/services/tests/reimbursements-logic.test.ts	New Vitest suite covering the extracted reimbursement logic helpers.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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