Update src/ColumnizerLib/ILogLine.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: Hirogen

src/ColumnizerLib/ILogLine.cs

@@ -11,8 +11,34 @@ public interface ILogLine : ITextValue
     #endregion
 }
 
+/// <summary>
+/// Represents a single log line, including its full text and line number.
+/// </summary>
+/// <remarks>
+/// <para>
+/// <b>Purpose:</b> <br/>
+/// The <c>LogLine</c> struct encapsulates the content and line number of a log entry. It is used throughout the
+/// columnizer and log processing infrastructure to provide a strongly-typed, immutable representation of a log line.
+/// </para>
+/// <para>
+/// <b>Usage:</b> <br/>
+/// This struct implements the <see cref="ILogLine"/> interface, allowing it to be used wherever an <c>ILogLine</c>
+/// is expected. It provides value semantics and is intended to be lightweight and efficiently passed by value.
+/// </para>
+/// <para>
+/// <b>Relationship to ILogLine:</b> <br/>
+/// <c>LogLine</c> is a concrete, immutable implementation of the <see cref="ILogLine"/> interface, providing
+/// properties for the full line text and its line number.
+/// </para>
+/// <para>
+/// <b>Why struct instead of record:</b> <br/>
+/// A <c>struct</c> is preferred over a <c>record</c> here to avoid heap allocations and to provide value-type
+/// semantics, which are beneficial for performance when processing large numbers of log lines. The struct is
+/// immutable (readonly), ensuring thread safety and predictability. The previous <c>record</c> implementation
+/// was replaced to better align with these performance and semantic requirements.
+/// </para>
+/// </remarks>
 public readonly struct LogLine (string fullLine, int lineNumber) : ILogLine
-{
     public string FullLine { get; } = fullLine;
 
     public int LineNumber { get; } = lineNumber;