Port the OpenAI families and add the model registry

app/MindWork AI Studio/Models/OpenAI/Gpt6AstraFamily.cs

@@ -0,0 +1,26 @@
+using static AIStudio.Provider.Capability;
+
+namespace AIStudio.Models.OpenAI;
+
+/// <summary>
+/// GPT-6 Astra.
+/// </summary>
+/// <remarks>
+/// Unlike the 5.5 and 5.6 models it reasons on every request: the effort reaches from low to max,
+/// and there is no setting which switches thinking off.
+/// </remarks>
+public sealed class Gpt6AstraFamily : ModelFamily
+{
+    /// <inheritdoc />
+    public override ModelVendor Vendor => ModelVendor.OPEN_AI;
+
+    /// <inheritdoc />
+    public override ModelSource Source => new("https://platform.openai.com/docs/models", new DateOnly(2026, 9, 11), "Ported unchanged from the rules in ProviderExtensions.OpenAI.cs: reasons on every request, both APIs.");
+
+    /// <inheritdoc />
+    protected override void Declare(ModelFamilyBuilder builder) =>
+        builder.Rule("gpt-6-astra").AsPrefix()
+            .Capabilities(TEXT_INPUT | MULTIPLE_IMAGE_INPUT | TEXT_OUTPUT | FUNCTION_CALLING | WEB_SEARCH)
+            .Apis(RESPONSES_API | CHAT_COMPLETION_API)
+            .Reasoning(ReasoningSupport.ALWAYS);
+}