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

app/MindWork AI Studio/Tools/PluginSystem/I18N.cs

@@ -1,17 +1,38 @@
+using System.Globalization;
+
 namespace AIStudio.Tools.PluginSystem;
 
 public class I18N : ILang
 {
     public static readonly I18N I = new();
     private static readonly ILogger<I18N> LOG = Program.LOGGER_FACTORY.CreateLogger<I18N>();
-    
+
     private ILanguagePlugin? language;
-    
+
     private I18N()
     {
     }
 
-    public static void Init(ILanguagePlugin language) => I.language = language;
+    /// <summary>
+    /// How the language in use writes its numbers, or the invariant culture while none is loaded.
+    /// </summary>
+    /// <remarks>
+    /// A number standing inside a translated sentence has to be written the way that language
+    /// writes numbers. AI Studio's language is chosen in its own settings and never moves the
+    /// thread's culture along with it, so a number formatted from the thread comes out with English
+    /// separators inside a German sentence. It lives here because it is the same decision as the
+    /// texts: whoever picked the language picked how its numbers look.
+    ///
+    /// Components which already hold the active plugin may keep deriving it themselves. This is for
+    /// the code which has no plugin to ask -- a provider building an error message, say.
+    /// </remarks>
+    public CultureInfo Culture { get; private set; } = CultureInfo.InvariantCulture;
+
+    public static void Init(ILanguagePlugin language)
+    {
+        I.language = language;
+        I.Culture = CommonTools.DeriveActiveCultureOrInvariant(language.IETFTag);
+    }
 
     #region Implementation of ILang