test: enhance and harden QA suites (e2e, jwt, settlement, invoice.service)

[CeceOs92]

Enhances and optimizes four test files per issues #346-#349. All four suites failed to compile on dev (garbled code from #424 / #431), so this also lands the minimal source fixes needed to unblock them.

Target suites: 0 -> 101 passing tests.

Source fixes (prerequisite):

• invoice.service.ts: remove dead try/catch block spliced into getInvoiceTokenHolders (referenced undefined uploadResult / input).
• User.model.ts: replace invalid Omit<User,"deleted_at"> return type on toPublicDTO with an explicit Pick<>; restore missing class-closing brace.
• Invoice.model.ts: readonly transition-map type; restore missing brace; drop now-unused BeforeInsert/BeforeUpdate imports.

#346 full-flow.e2e.test.ts:

• extract duplicated seller/investor challenge-response into authenticateViaChallenge() helper
• wrap beforeAll harness bring-up in try/catch with structured logging
• add jest.setTimeout(30_000) against sporadic CI timeouts

#347 auth-jwt-validation.test.ts:

• build the test app once in beforeAll instead of ~25 times
• add signToken / getMe / expectRejected helpers; collapse ~20 cases into two it.each tables
• assert the middleware's real granular messages (Invalid token payload., User no longer exists.); all failure modes still return the 401 envelope

#348 settlement.integration.test.ts:

• fix 2 broken tests: the log lookup matched the funding transition (published -> funded) emitted by fullyFundInvoice, not settlement's
• add findSettlementTransitionLog / findSettlementCompletionLog helpers and route all log assertions through them

#349 invoice.service.test.ts:

• add buildCreateInput() factory and wireCreatePassthrough() helper
• convert net-amount tests to an it.each table exercising the real calculation, keeping the 29.99 @ 0.5% IEEE-754 regression guard

Closes #346
Closes #347
Closes #348
Closes #349

[drips-wave]

@CeceOs92 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits