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/runbooks.md

@@ -0,0 +1,85 @@
+# JPA Platform Runbooks
+
+Operator procedures for the failures this platform is designed to surface rather than hide.
+
+## A transaction reported completion unknown
+
+**Signal:** `jpa.transaction.completion.unknown` incremented; a `CompletionUnknownRecord` in the
+reconciliation channel.
+
+**What it means:** the commit may or may not have happened. It is not a rollback.
+
+**Do not** re-run the use case. That is what the platform refused to do automatically, for the same
+reason.
+
+**Procedure:**
+
+1. Take the `transactionKey` from the record.
+2. Check the idempotency record for that key.
+3. Check the business row the use case would have written.
+4. Check the outbox for a corresponding event.
+5. If all three agree the write happened, mark the record `COMMITTED` and stop.
+6. If all three agree it did not, the use case may be re-run.
+7. If they disagree or are inconclusive, leave it `STILL_UNKNOWN` and escalate. An inconclusive
+   answer is a legitimate outcome; guessing is not.
+
+A record with no `transactionKey` cannot be resolved automatically — use the operation name and
+timestamp.
+
+## Deadlock or serialization rate rising
+
+**Signal:** `jpa.retry.attempt` rising; `jpa.retry.exhausted` non-zero.
+
+Retries are expected. Exhaustion is not.
+
+1. Group `jpa.retry.attempt` by operation. A single operation dominating means a hot row or an
+   inconsistent lock order.
+2. For deadlocks, check whether two operations take the same rows in opposite orders — that is a
+   code fix, not a tuning one.
+3. For serialization failures under `SERIALIZABLE`, confirm the isolation is actually required.
+4. Only then consider raising `maxAttempts`. A larger budget on a hot row converts a fast failure
+   into a slow one.
+
+## Pool exhaustion
+
+**Signal:** connection acquisition timeouts; `PoolMeasurement.pending` non-zero.
+
+1. Check `REQUIRES_NEW` usage. It takes a second connection while pinning the first, so the pool
+   must satisfy `(threads x (1 + depth)) + 1`.
+2. Check for streaming outside a bounded scope — a `Stream` returned past the transaction holds its
+   connection until the pool notices.
+3. Check for external calls inside a DB transaction. The design forbids them precisely because an
+   HTTP timeout then holds a connection for its whole duration.
+
+## Flyway validation failed at startup
+
+The deployment is running against a schema it was not built for. It failed closed, which is correct.
+
+1. Read the reported error codes (the messages are deliberately not propagated).
+2. `CHECKSUM_MISMATCH` — an applied migration was edited afterwards. Find which change is missing
+   from this database. **Do not run `repair`**: it rewrites history to match the scripts, which
+   resolves the symptom by deleting the evidence.
+3. `MISSING_SCRIPT` — a migration applied here is not in this build. Usually a rollback to an older
+   artifact.
+
+## An invalid index exists
+
+**Signal:** `FailedConcurrentIndexRecovery.invalidIndexes()` is non-empty.
+
+A concurrent build failed. The index is ignored by the planner and maintained by every write.
+
+1. Confirm no build is currently running. An in-progress build looks identical in the catalog.
+2. Run the reported `DROP INDEX CONCURRENTLY` outside a migration.
+3. Re-apply the index migration.
+
+The platform does not drop these automatically: on a rolling deploy every instance would race to
+drop an index another instance was about to finish building.
+
+## The runtime role failed verification
+
+Startup refused because the runtime credential holds `CREATE`, or `search_path` contains an
+unapproved schema.
+
+This is not a false positive to be worked around. Re-provision from
+`infra/jpa/roles/runtime-roles.sql`; the application's credential having DDL is the condition that
+makes every other schema guarantee unenforceable.