Port the Mistral families, including the release date logic

app/MindWork AI Studio/Models/Mistral/PixtralFamily.cs

@@ -0,0 +1,24 @@
+using static AIStudio.Provider.Capability;
+
+namespace AIStudio.Models.Mistral;
+
+/// <summary>
+/// Pixtral, the Mistral models built to look at pictures.
+/// </summary>
+/// <remarks>
+/// They read images from the first release, so nothing here depends on a date.
+/// </remarks>
+public sealed class PixtralFamily : ModelFamily
+{
+    /// <inheritdoc />
+    public override ModelVendor Vendor => ModelVendor.MISTRAL_AI;
+
+    /// <inheritdoc />
+    public override ModelSource Source => new("https://docs.mistral.ai/getting-started/models/models_overview/", new DateOnly(2026, 9, 11), "Ported unchanged from the rules in ProviderExtensions.Mistral.cs: images in every release.");
+
+    /// <inheritdoc />
+    protected override void Declare(ModelFamilyBuilder builder) =>
+        builder.Rule("pixtral").AsSegment()
+            .Capabilities(TEXT_INPUT | MULTIPLE_IMAGE_INPUT | TEXT_OUTPUT | FUNCTION_CALLING)
+            .Apis(CHAT_COMPLETION_API);
+}