added common function to derive CultureInfo for formatting from the active plugins IETF Tag

app/MindWork AI Studio/Tools/CommonTools.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Text;
 
 namespace AIStudio.Tools;
@@ -19,4 +20,32 @@ public static class CommonTools
         
         return sb.ToString();
     }
-}
+
+    /// <summary>
+    /// Resolves a <see cref="CultureInfo"/> from the active language plugin's IETF tag.
+    /// </summary>
+    /// <param name="ietfTag">The IETF language tag provided by the active language plugin.</param>
+    /// <returns>The matching culture when the tag is valid; otherwise <see cref="CultureInfo.InvariantCulture"/>.</returns>
+    public static CultureInfo DeriveActiveCultureOrInvariant(string? ietfTag)
+    {
+        if (string.IsNullOrWhiteSpace(ietfTag))
+            return CultureInfo.InvariantCulture;
+
+        try
+        {
+            return CultureInfo.GetCultureInfo(ietfTag);
+        }
+        catch (CultureNotFoundException)
+        {
+            return CultureInfo.InvariantCulture;
+        }
+    }
+    
+    /// <summary>
+    /// Formats a timestamp using the short date and time pattern of the specified culture.
+    /// </summary>
+    /// <param name="timestamp">The timestamp to format.</param>
+    /// <param name="culture">The culture whose short date and time pattern should be used.</param>
+    /// <returns>The localized timestamp string.</returns>
+    public static string FormatTimestampToGeneral(DateTime timestamp, CultureInfo culture) => timestamp.ToString("g", culture);
+}