feat: Implement OpenRouter model discovery and endpoints

- Added OpenRouterModelDiscovery class for managing model listings and metadata resolution.
- Introduced OpenRouterModelEndpointsResponse and OpenRouterModelsResponse classes for handling API responses.
- Created OpenRouterModelQuery class to encapsulate query parameters for model listing.
- Updated ModelProfile to include OPENROUTER as a model provider.
- Enhanced ModelProfileService to handle default values for maxTokens and maxContextLength.
- Added OpenRouterClientTest for testing model discovery and chat completion functionalities.
- Configured application-test.properties and local-openrouter-chatcompletion.properties for OpenRouter integration.

src/test/java/de/extio/lmlib/client/openrouter/OpenRouterClientTest.java

@@ -0,0 +1,117 @@
+package de.extio.lmlib.client.openrouter;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.test.context.DynamicPropertyRegistry;
+import org.springframework.test.context.DynamicPropertySource;
+import org.springframework.test.context.TestPropertySource;
+
+import de.extio.lmlib.client.ClientService;
+import de.extio.lmlib.client.Conversation;
+import de.extio.lmlib.grader.Grader2;
+import de.extio.lmlib.profile.ModelProfile;
+import de.extio.lmlib.profile.ModelProfileService;
+
+@Disabled("This test requires a valid OpenRouter API key")
+@SpringBootTest(webEnvironment = WebEnvironment.NONE)
+@SpringBootConfiguration
+@EnableAutoConfiguration
+@TestPropertySource("classpath:/application-test.properties")
+public class OpenRouterClientTest {
+
+	private final static String API_KEY = ""; // Enter your OpenRouter API key here for testing
+
+	private static final Logger LOGGER = LoggerFactory.getLogger(OpenRouterClientTest.class);
+
+	@DynamicPropertySource
+	static void registerProperties(final DynamicPropertyRegistry registry) {
+		registry.add("OPENROUTER_API_KEY", () -> API_KEY);
+	}
+
+	@Autowired
+	private OpenRouterClient openRouterClient;
+
+	@Autowired
+	private OpenRouterModelDiscovery openRouterModelDiscovery;
+
+	@Autowired
+	private ModelProfileService modelProfileService;
+
+	@Autowired
+	private ClientService clientService;
+
+	@Test
+	void modelDiscovery() throws Exception {
+		final var modelProfile = this.modelProfile();
+		final var models = this.openRouterModelDiscovery.listModels(modelProfile, new OpenRouterModelQuery(true, null, List.of(), List.of()), true);
+		LOGGER.info("Models: {}", models);
+		assertFalse(models.isEmpty());
+		assertFalse(models.getFirst().getId().isBlank());
+		final var resolvedModelName = models.getFirst().getId();
+		LOGGER.info("Resolved model name: {}", resolvedModelName);
+		final var metadata = this.openRouterModelDiscovery.resolveModelMetadata(modelProfile, resolvedModelName, true);
+		LOGGER.info("Metadata: {}", metadata);
+		assertEquals(resolvedModelName, metadata.modelId());
+		assertTrue(metadata.contextLength() > 0);
+		assertEquals(ModelProfile.ModelProvider.OPENROUTER, this.clientService.getClient(modelProfile).getModelProvider());
+	}
+
+	@Test
+	void chatCompletion() throws Exception {
+		final var modelProfile = this.modelProfile();
+		final var completion = this.openRouterClient.conversation(
+				modelProfile,
+				Conversation.create("You are a helpful assistant", "Say the color is green"),
+				null,
+				false);
+
+		LOGGER.info(completion.reasoning());
+		LOGGER.info(completion.response());
+
+		assertTrue(Grader2.assessScoreBinary("Does the text mention the color green?", completion.response(), modelProfile, this.clientService));
+	}
+
+	@Test
+	void streamChatCompletion() throws Exception {
+		final var modelProfile = this.modelProfile();
+		final var conversation = Conversation.create("You are a helpful assistant", "I would like to play a game of chess.");
+		conversation.addTurn(new Conversation.Turn(Conversation.TurnType.ASSISTANT, "Which opening do you choose?"));
+		conversation.addTurn(new Conversation.Turn(Conversation.TurnType.USER, "You choose, but explain the opening to me."));
+		final var responseBuilder = new StringBuilder();
+		final var reasoningBuilder = new StringBuilder();
+		final var completion = this.openRouterClient.streamConversation(modelProfile, conversation, chunk -> {
+			if (chunk.reasoningContent() != null) {
+				System.out.print(chunk.reasoningContent());
+				reasoningBuilder.append(chunk.reasoningContent());
+			}
+			if (chunk.content() != null) {
+				System.out.print(chunk.content());
+				responseBuilder.append(chunk.content());
+			}
+		}, null, false);
+
+		assertEquals(completion.response(), responseBuilder.toString());
+		if (completion.reasoning() != null) {
+			assertEquals(completion.reasoning(), reasoningBuilder.toString());
+		}
+		assertTrue(Grader2.assessScoreBinary("Does the text explain a chess opening?", completion.response(), modelProfile, this.clientService));
+	}
+
+	private ModelProfile modelProfile() {
+		return this.modelProfileService.getModelProfile("profile.model.openrouter");
+	}
+
+}