feat(jpa): implement the JPA relational persistence platform

Implements the Stable and Experimental JPA persistence platform designs
against real PostgreSQL, adapted to this repository's fail-closed 19-leaf
registry.

The design models the platform as 25 Gradle projects. `src/settings.gradle`
throws unless the registry holds exactly 19 leaves, so the plan's modules
become packages inside `:adapter:outbound:persistence-jpa` (starter in
`:app-bootstrap`, testkit in its own source set). The full mapping, the
renames this repository's naming gate required, and every deliberate
substitution are recorded in `docs/jpa/repository-adaptation.md`.

Seven Docker-backed lanes replace the plan's seven JVM test suites. Each
fails closed: a lane that discovers nothing, or a container that cannot
start, is an error rather than a skip.

Three defects the contracts found against a real server:

- `CommitFailureClassifier` treated only SQLSTATE 40003, class 08, and
  transport breaks as completion-unknown. A backend terminated mid-commit
  reports 57P01, and the commit record may already be in the WAL — so a
  possibly-committed transaction could be re-run. 57P01/57P02/57P03 now
  classify as completion-unknown.
- `SchemaTenantMigrationOrchestrator` recorded `MigrateResult`'s target
  version, which is empty for a tenant already current, reporting migrated
  tenants as unmigrated during a partial rollout. It now reads the applied
  version back from the tenant's schema history.
- `JpaStreamExecutor` checked only the declared return type for reactive
  publishers, and `RegisteredPostgreSqlCopyLoader` passed the COPY timeout
  to `SET`, which is parsed before parameter binding.

`JpaModuleBoundaryTest` enforces the plan's module map as package rules;
`verifyCleanArchitectureDependencies` governs edges between leaves and
cannot see these. Its first assertion is that the import is non-empty,
because every rule under it is a `noClasses()` rule and would pass
vacuously on an empty import.

Verified: 128 container tests across all seven lanes, 1183 unit tests,
`:adapter:outbound:persistence-jpa:check`, `:app-bootstrap:check`,
`verifyCleanArchitectureDependencies`, `verifyOneTypePerFile`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/adr/ADR-JPA-005-postgresql-real-contract.md

@@ -0,0 +1,38 @@
+# ADR-JPA-005 — Contracts run against real PostgreSQL
+
+- Status: Accepted
+- Date: 2026-08-11
+- Design: §40
+
+## Context
+
+An in-memory database makes tests fast and hermetic. A container makes them slow and requires
+Docker.
+
+## Decision
+
+Every persistence contract runs against real PostgreSQL 16, 17, and 18 in containers. H2 remains a
+local-development convenience and never satisfies a contract. The lanes fail closed when Docker is
+absent rather than skipping.
+
+## Consequences
+
+The behaviours these contracts verify either do not exist in H2 or differ there: SQLSTATE values for
+the same violation, `FOR UPDATE SKIP LOCKED` semantics, JSONB operators, range types, concurrent
+index builds, `search_path` privileges, and the generated SQL for a paged collection fetch. A green
+H2 run is evidence that the code compiles and runs — not that any of the above holds.
+
+Three versions rather than one because the platform claims three. A contract suite that ran only on
+16 would make "Stable on 17 and 18" an assumption.
+
+Skipping on missing Docker is the failure mode this decision most wants to avoid: a skipped contract
+reports success, and CI eventually inherits that silence. `PostgreSqlContainerFactory.assertDockerAvailable()`
+throws instead.
+
+The cost is that the contract lanes need Docker and take minutes. The unit lane stays hermetic and
+fast, and is where most tests live; the container lanes verify the things only a real server can
+answer.
+
+## Enforcement
+
+`PostgreSqlVersion.stable()`; `PostgreSqlContainerFactory`; release gate `postgresql-contract`.