Add image processing benchmarks and UI folder open buttons

- Added MaddoShared.Benchmarks project with BenchmarkDotNet for comprehensive image processing performance tests (parallel, chunk, size, stress).
- Included helper for generating test images and custom configs to ensure InProcess toolchain for .NET Windows compatibility.
- Added cross-platform scripts to run benchmarks easily.
- Updated .gitignore for benchmark artifacts and temp files.
- Exposed GetFilesToProcessPublic in ImageCreationStuff for testability.
- Added file name sanitization in ImageCreatorSharp to prevent IO errors.
- Enhanced WinForms UI: added "Open" buttons for source/destination folders, handled folder opening in Explorer, and improved user messaging and layout.
- Updated solution file to include new benchmark project.

MaddoShared/ImageCreationStuff.cs

@@ -52,6 +52,15 @@ namespace MaddoShared
                 $"{stopwatch.Elapsed.Hours}h {stopwatch.Elapsed.Minutes}m {stopwatch.Elapsed.Seconds}s ({stopwatch.Elapsed.TotalSeconds}s)";
         }
 
+        /// <summary>
+        /// Gets the list of files that will be processed based on the provided options.
+        /// Useful for benchmarking and testing to understand the scope of work.
+        /// </summary>
+        public List<FileData> GetFilesToProcessPublic(Options options)
+        {
+            return GetFilesToProcess(options);
+        }
+
         public async Task ProcessImagesParallel(
             Options options,
             ConcurrentBag<string> results,