Layer 1 Part B: NaivePrReviewService and PrReviewResource (teaching baseline)

[mdproctor]

Context

Layer 1 of the devtown tutorial has two parts. Part A (Epics 1–2) established the domain vocabulary and scaffold. Part B — the naive PR review service — is the teaching baseline that every subsequent layer displaces.

This issue covers Part B. It is a prerequisite for Epic 3 (casehub-engine, Layer 5): the Layer 5 LAYER-LOG gap comments reference code in `NaivePrReviewService` by design, and the `@DefaultBean` displacement pattern requires a bean to displace.

What to build

`app/src/main/java/io/casehub/devtown/app/NaivePrReviewService.java`

• `@ApplicationScoped @DefaultBean` implementing `PrReviewApplicationService` (interface to define)
• Direct calls to stub specialist services — no CaseHub, no obligations, no audit
• Gap comments on every compliance gap:
  • No attribution — which agent reviewed this?
  • No response SLA — reviewer can sit indefinitely
  • No formal DECLINE — scope boundaries not structurally captured
  • No tamper-evident audit trail
  • No trust weighting

`app/src/main/java/io/casehub/devtown/app/PrReviewResource.java`

• `POST /api/reviews` — thin REST dispatcher injecting the port interface
• Auth-retrofit ready: no auth logic in the resource body

Test

• Plain `new`, no Quarkus — verify the naive service executes and gap comments are exercisable

Reference

• Layer 1 full spec: `LAYER-LOG.md` §Layer 1 Part B
• Displacement pattern: `@DefaultBean` yielded by any non-default `@ApplicationScoped` impl
• Tutorial teaching objective: `../parent/docs/tutorial-strategy.md §7.5.1` Layer 1
• Epic 3 (Layer 5): devtown#10 — depends on this issue

Refs devtown#8, devtown#9