Renamed to QR Script

- Split into three projects: Library, Console, and Tests
- Library compiles as QRScript.Interpreter to avoid conflicts

QRScript/StringExtensions.cs

@@ -0,0 +1,56 @@
+namespace QRScript.Extensions;
+
+using System.Text;
+
+/// <summary>
+/// Provides extension methods for common string transformations and validations.
+/// </summary>
+public static class StringExtensions
+{
+    /// <summary>
+    /// Encodes the current string instance to Base64 using Unicode encoding.
+    /// </summary>
+    /// <param name="input">The input string to encode.</param>
+    /// <returns>A Base64-encoded version of the input string.</returns>
+    /// <remarks>
+    /// This uses Unicode (UTF-16) encoding, which is standard in .NET strings.
+    /// </remarks>
+    public static string ToBase64(this string input)
+    {
+        if (input is null)
+            throw new ArgumentNullException(nameof(input));
+
+        byte[] bytes = Encoding.Unicode.GetBytes(input);
+        return Convert.ToBase64String(bytes);
+    }
+
+    /// <summary>
+    /// Joins an array of strings into a single string separated by the system's newline.
+    /// </summary>
+    /// <param name="lines">Array of strings to join.</param>
+    /// <returns>A single string composed of all input lines, separated by newlines.</returns>
+    public static string JoinLines(this IEnumerable<string> lines)
+    {
+        if (lines is null)
+            throw new ArgumentNullException(nameof(lines));
+
+        return string.Join(Environment.NewLine, lines);
+    }
+
+    /// <summary>
+    /// Determines whether the string exceeds the specified character length limit.
+    /// </summary>
+    /// <param name="text">The input string to evaluate.</param>
+    /// <param name="limit">The maximum number of allowed characters.</param>
+    /// <returns><c>true</c> if the string's length is greater than or equal to <paramref name="limit"/>; otherwise, <c>false</c>.</returns>
+    public static bool ExceedsLengthLimit(this string text, int limit)
+    {
+        if (text is null)
+            throw new ArgumentNullException(nameof(text));
+
+        if (limit < 0)
+            throw new ArgumentOutOfRangeException(nameof(limit), "Limit must be non-negative.");
+
+        return text.Length >= limit;
+    }
+}