Refactor AddWatermarkIfNeeded for clarity and readability

Refactored the `AddWatermarkIfNeeded` method in the `ImageController` class to improve readability and logic clarity. The method now returns early if the watermark is not enabled, should be skipped, or if the file extension is `.gif`. This change simplifies the code by removing nested conditions and making the watermarking logic more straightforward. The use of `using var` for the `ImageWatermarker` instance remains unchanged to ensure proper resource disposal.

src/Moonglade.Web/Controllers/ImageController.cs

@@ -98,23 +98,21 @@ public async Task<IActionResult> Image([Required] IFormFile file, [FromQuery] bo
 
     private byte[] AddWatermarkIfNeeded(MemoryStream stream, string ext, bool skipWatermark)
     {
-        if (blogConfig.ImageSettings.IsWatermarkEnabled && !skipWatermark && !ext.Equals(".gif", StringComparison.OrdinalIgnoreCase))
-        {
-            using var watermarker = new ImageWatermarker(stream, ext, blogConfig.ImageSettings.WatermarkSkipPixel);
-            return watermarker.AddWatermark(
-                blogConfig.ImageSettings.WatermarkText,
-                Color.FromRgba(128, 128, 128, (byte)blogConfig.ImageSettings.WatermarkColorA),
-                WatermarkPosition.BottomRight,
-                15,
-                blogConfig.ImageSettings.WatermarkFontSize)?.ToArray();
-        }
+        if (!blogConfig.ImageSettings.IsWatermarkEnabled || skipWatermark) return null;
 
         if (ext.Equals(".gif", StringComparison.OrdinalIgnoreCase))
         {
             logger.LogInformation($"Skipped watermark for extension name: {ext}");
+            return null;
         }
 
-        return null;
+        using var watermarker = new ImageWatermarker(stream, ext, blogConfig.ImageSettings.WatermarkSkipPixel);
+        return watermarker.AddWatermark(
+            blogConfig.ImageSettings.WatermarkText,
+            Color.FromRgba(128, 128, 128, (byte)blogConfig.ImageSettings.WatermarkColorA),
+            WatermarkPosition.BottomRight,
+            15,
+            blogConfig.ImageSettings.WatermarkFontSize)?.ToArray();
     }
 
     private bool ShouldKeepOriginal(bool skipWatermark)