add architecture skeleton

GymLogAI.AI/OpenRouterEmbeddingClient.cs

@@ -0,0 +1,37 @@
+using System.Net.Http.Json;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+
+namespace GymLogAI.AI;
+
+public sealed class OpenRouterEmbeddingClient(
+    HttpClient httpClient,
+    IOptions<OpenRouterOptions> options,
+    ILogger<OpenRouterEmbeddingClient> logger)
+{
+    private readonly OpenRouterOptions _options = options.Value;
+
+    public async Task<float[]?> GenerateAsync(string input, CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(_options.ApiKey))
+        {
+            logger.LogInformation("OpenRouter API key is not configured. Returning stubbed embedding.");
+            return null;
+        }
+
+        using var request = new HttpRequestMessage(HttpMethod.Post, "embeddings")
+        {
+            Content = JsonContent.Create(new
+            {
+                model = _options.EmbeddingModel,
+                input
+            })
+        };
+
+        request.Headers.Authorization = new("Bearer", _options.ApiKey);
+        var response = await httpClient.SendAsync(request, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+        return null;
+    }
+}