Simplify signature UIImage export (#66)

# Simplify signature `UIImage` export

## ♻️ Current situation & Problem
The current signature export logic manually reads all strokes from the
drawing and sets them to black before converting to an UI image. This
can be done simpler via
`.withRenderingMode(.alwaysTemplate).withTintColor(.black)`


## ⚙️ Release Notes 
- Simplify signature `UIImage` export
- Fixed LFS consent document files in unit tests


## 📚 Documentation
Updated doc


## ✅ Testing
Tested locally


## 📝 Code of Conduct & Contributing Guidelines 

By submitting creating this pull request, you agree to follow our [Code
of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md).

Sources/SpeziOnboarding/Consent/Export/ConsentDocument+Export.swift

@@ -39,31 +39,18 @@ extension ConsentDocument {
 
     #if !os(macOS)
     private var signatureImage: UIImage {
-        var updatedDrawing = PKDrawing()
-
-        for stroke in signature.strokes {
-            // As the `PKDrawing.image()` function automatically converts the ink color dependent on the used color scheme (light or dark mode),
-            // force the ink used in the `UIImage` of the `PKDrawing` to always be black by adjusting the signature ink according to the color scheme.
-            let blackStroke = PKStroke(
-                ink: PKInk(stroke.ink.inkType, color: colorScheme == .light ? .black : .white),
-                path: stroke.path,
-                transform: stroke.transform,
-                mask: stroke.mask
-            )
-
-            updatedDrawing.strokes.append(blackStroke)
-        }
-
         #if os(iOS)
         let scale = UIScreen.main.scale
         #else
         let scale = 3.0 // retina scale is default
         #endif
 
-        return updatedDrawing.image(
+        // As the `PKDrawing.image()` function automatically converts the ink color dependent on the used color scheme (light or dark mode),
+        // force the tint color used in the `UIImage` to `black`.
+        return signature.image(
             from: .init(x: 0, y: 0, width: signatureSize.width, height: signatureSize.height),
             scale: scale
-        )
+        ).withRenderingMode(.alwaysTemplate).withTintColor(.black)
     }
     #endif
 }

Sources/SpeziOnboarding/Consent/Export/ConsentDocumentExportRepresentation+Render.swift

@@ -51,8 +51,9 @@ extension ConsentDocumentExportRepresentation {
             markdown: markdown,
             options: .init(interpretedSyntax: .inlineOnlyPreservingWhitespace)
         )) ?? AttributedString(String(localized: "MARKDOWN_LOADING_ERROR", bundle: .module))
-
-        markdownString.font = configuration.fontSettings.documentContentFont
+
+        // Indirection needed to hide `Sendable` warnings of `NSFont` on macOS
+        markdownString.mergeAttributes(.init([.font: configuration.fontSettings.documentContentFont]))
 
         return PDFAttributedText(text: NSAttributedString(markdownString))
     }