test: generate the JWT test keys, drop application-dev.yml

The dev config held real keys. Local dev config now lives outside the repo; integration tests create a fresh Ed25519 keypair per run.

.gitignore

@@ -35,3 +35,7 @@ build/
 ### Local secrets and generated files ###
 .env
 effective-pom
+
+### Local dev config, never committed ###
+application-dev.yml
+application-dev.yaml