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/jpa/transaction-guide.md

@@ -0,0 +1,66 @@
+# Transaction Guide
+
+Design §15-§20. What owns a transaction, what may be retried, and what must never be.
+
+## The application service owns the boundary
+
+Repository adapters do not open transactions. The use case does, through `TransactionPort` or
+`JpaTransactionExecutor`, because the unit of work is a business decision and only the use case
+knows where it starts and ends.
+
+Open Session In View is off in every runtime profile. It is on by default in Spring Boot, which is
+why `JpaDangerousConfigurationGuard` fails startup rather than trusting configuration review.
+
+## Profiles
+
+A `TransactionProfile` fixes propagation, isolation, timeout, read-only, and the retry budget. A
+write profile must carry a positive finite timeout — the type refuses to represent one without —
+because an unbounded write transaction holds a connection, its locks, and its row versions for as
+long as one stuck statement takes.
+
+`REQUIRES_NEW` is opt-in. It acquires a second physical connection while pinning the first, so a
+profile using it must be paired with the pool-pressure evidence in design §38:
+
+```text
+maximumPoolSize >= (concurrent_threads x (1 + max_requires_new_depth)) + 1
+```
+
+## Retry is per use case, never per statement
+
+`FullTransactionRetryCoordinator` re-enters the executor, which produces a new transaction and a new
+Persistence Context for every attempt. That granularity is the whole point: an optimistic conflict
+means the state the attempt computed against is no longer the committed state, so re-issuing the
+same statement would compute the same wrong answer. The domain rules have to run again against
+reloaded data.
+
+Retryable: serialization failure (`40001`), deadlock (`40P01`), optimistic conflict.
+Not retryable: constraint violations, schema mismatch, query timeout, and anything unclassified.
+
+Two additional refusals, independent of budget:
+
+- An attempt that declared an irreversible external effect through `IrreversibleSideEffectContext`.
+  Rollback reverses database work only; an email or a card charge has already changed the world.
+- Anything completion-unknown.
+
+## Completion unknown
+
+`TransactionCompletionUnknownException` is never retried, and the type system enforces it twice:
+`JpaFailureContext` refuses to represent a retryable completion-unknown failure, and the exception
+rebuilds its context through the safe factory whatever it is handed.
+
+`EvidenceAwareJpaTransactionManager` marks the phase `COMMITTING` immediately before delegating to
+the provider commit and never after. If the network, the JVM, or the server dies inside that call,
+the last thing written is "we asked, we do not know" — which is exactly the state that must not be
+mistaken for a rollback.
+
+Recovery is reconciliation, not retry:
+
+```text
+record the transaction key -> check the idempotency record
+                           -> check the business row
+                           -> check the outbox
+                           -> still undetermined? reconciliation queue
+```
+
+`CompletionUnknownRecorder` writes that record through a channel outside the unknown transaction.
+Writing it through the same connection would make the audit trail share the failure it documents.