Rebuilt how AI Studio knows what a model can do (#960)

app/MindWork AI Studio/Models/TokenizerRef.cs

@@ -0,0 +1,24 @@
+namespace AIStudio.Models;
+
+/// <summary>
+/// Points at the tokenizer a model uses, without fetching it.
+/// </summary>
+/// <remarks>
+/// Only the reference is recorded here. Obtaining a tokenizer is a feature of its own, and today
+/// only the Hugging Face kind could be resolved at all; the other kinds document what would have to
+/// happen. Unknown means the built-in default tokenizer, which is what every model uses today.
+/// </remarks>
+/// <param name="Kind">What sort of tokenizer this is, which decides how the name would be resolved.</param>
+/// <param name="Id">The name, in whatever spelling the kind uses. Meaningless unless the reference is known.</param>
+public readonly record struct TokenizerRef(TokenizerKind Kind, string Id)
+{
+    /// <summary>
+    /// The tokenizer of a model we have no statement about: the built-in default one.
+    /// </summary>
+    public static readonly TokenizerRef UNKNOWN = new(TokenizerKind.UNKNOWN, string.Empty);
+
+    /// <summary>
+    /// Whether this reference names something. Read the ID only when it does.
+    /// </summary>
+    public bool IsKnown => this.Kind is not TokenizerKind.UNKNOWN && !string.IsNullOrWhiteSpace(this.Id);
+}