feat(api): add unauthenticated health endpoints

Add GET /api/v1/health/live and GET /api/v1/health/ready per ADR 0044.

- live returns a fixed 200 {"status":"live"} whenever the process serves.
- ready returns 200 {"status":"ready"} only when module startup has
  completed (and shutdown has not begun) and a database ping succeeds
  within 2s; otherwise a fixed 503 {"code":"NOT_READY"}.
- The ping runs on the shared pool as one simple-protocol message with
  a transaction-local statement_timeout, so PostgreSQL cancels a stalled
  statement; the pool discards the connection on failure.
- At most one ping is ever unsettled: probes share its outcome and, once
  its deadline passes, answer 503 immediately until it settles.
- Both routes set Cache-Control: no-store, accept GET only (405 with
  Allow: GET otherwise, HEAD included), never resolve a principal, and
  are mounted in app.ts beside, never inside, /api/v1/modules/.
- createApiApp gains a required `health` option; startApi supplies it
  and clears module readiness when shutdown begins.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/api/tests/support/ready-health.ts

@@ -0,0 +1,10 @@
+import type { ApiHealthOptions } from "../../src/health-routes.js";
+
+/** Readiness inputs for a composition whose tests do not exercise health: the database answers and
+ * module startup has completed. Health behavior itself is tested in `../health-routes.test.ts`. */
+export function readyHealth(): ApiHealthOptions {
+  return {
+    checkDatabase: async () => undefined,
+    isModuleStartupComplete: () => true,
+  };
+}