Indent blank lines and address avatar crop review feedback

Indent the new method's blank lines to satisfy SwiftFormat's
indent-blank-lines rule, which failed the Tests CI jobs.

Also address review findings on the crop itself:
- Request a 256pt thumbnail box at both donation sites so cropping a
  scaled (aspect-fit) thumbnail to its minor axis keeps enough
  resolution for the share sheet's circle.
- Round the draw offsets to whole pixels so odd-sized crops blit
  instead of resampling.
- Log when fetched avatar data can't be decoded rather than silently
  swapping in the placeholder, and document the non-obvious
  format.scale pinning.

NSE/Sources/NotificationContentBuilder.swift

@@ -257,10 +257,13 @@ nonisolated struct NotificationContentBuilder {
         let image: INImage
         if !forcePlaceholder,
            let mediaSource = icon.mediaSource {
-            switch await mediaProvider.loadThumbnailForSource(source: mediaSource, size: .init(width: 100, height: 100)) {
+            // Request a generous size so the square crop of a non-square avatar keeps enough resolution.
+            switch await mediaProvider.loadThumbnailForSource(source: mediaSource, size: .init(width: 256, height: 256)) {
             case .success(let data):
                 if let squareData = Avatars.squareAvatarImageData(from: data) {
                     fetchedImage = INImage(imageData: squareData)
+                } else {
+                    MXLog.error("Couldn't decode the fetched sender icon, using a placeholder.")
                 }
             case .failure(let error):
                 MXLog.error("Couldn't add sender icon: \(error)")