Add tests and implement StubBearer authentication for Signer endpoints

- Created SignerEndpointsTests to validate the SignDsse and VerifyReferrers endpoints.
- Implemented StubBearerAuthenticationDefaults and StubBearerAuthenticationHandler for token-based authentication.
- Developed ConcelierExporterClient for managing Trivy DB settings and export operations.
- Added TrivyDbSettingsPageComponent for UI interactions with Trivy DB settings, including form handling and export triggering.
- Implemented styles and HTML structure for Trivy DB settings page.
- Created NotifySmokeCheck tool for validating Redis event streams and Notify deliveries.

samples/runtime/java-demo/README.md

@@ -0,0 +1,5 @@
+# Java Demo Fixture
+
+Minimal archive tree that exercises the Java language analyzer during microbenchmarks. The `libs/demo.jar`
+artefact ships `META-INF/MANIFEST.MF` and `META-INF/maven/com.example/demo/pom.properties` entries so the
+analyzer can extract Maven coordinates and manifest metadata without pulling in large third-party jars.