Implement ImageCreatorImageSharp using SixLabors.ImageSharp for image processing

- Added ImageCreatorImageSharp class for image creation, handling EXIF orientation, resizing, and saving images.
- Replaced GDI+ dependencies with ImageSharp for cross-platform compatibility.
- Introduced methods for drawing text and logos on images, including handling transparency and positioning.
- Created a test plan for validating ImageCreatorImageSharp functionality, focusing on image resizing, text positioning, logo features, and EXIF orientation.
- Added documentation for the test plan outlining goals, project structure, and implementation notes.

MaddoShared.ImageSharpTests/Helpers/PixelInspector.cs

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+using System;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace MaddoShared.ImageSharpTests.Helpers
+{
+    public static class PixelInspector
+    {
+        public static int CountNonBackgroundPixels(string path, int x, int y, int width, int height, Rgba32 background, int tolerance = 0)
+        {
+            using var img = SixLabors.ImageSharp.Image.Load<Rgba32>(path);
+            var bx = Math.Max(0, x);
+            var by = Math.Max(0, y);
+            var bw = Math.Min(width, img.Width - bx);
+            var bh = Math.Min(height, img.Height - by);
+            if (bw <= 0 || bh <= 0) return 0;
+
+            int count = 0;
+            img.ProcessPixelRows(accessor =>
+            {
+                for (int yy = by; yy < by + bh; yy++)
+                {
+                    var row = accessor.GetRowSpan(yy);
+                    for (int xx = bx; xx < bx + bw; xx++)
+                    {
+                        var p = row[xx];
+                        if (!IsApproximatelyEqual(p, background, tolerance)) count++;
+                    }
+                }
+            });
+
+            return count;
+        }
+
+        private static bool IsApproximatelyEqual(Rgba32 a, Rgba32 b, int tol)
+        {
+            return Math.Abs(a.R - b.R) <= tol && Math.Abs(a.G - b.G) <= tol && Math.Abs(a.B - b.B) <= tol && Math.Abs(a.A - b.A) <= tol;
+        }
+    }
+}