fix: take orientation into account for border generation in ScreenshotUtil (#1977)

## Summary

Previously `ScreenshotUtil` used physical display size to draw a border
around the screen contents. Because of this, in landscape orientation
the border was shown as a broken square. This PR changes border drawing
to use logical screen size instead of a physical display size to take
orientation into account.

## Additional Context

* Tested on X4 in all 4 reading orientations. Behavior is now correct,
however it doesn't look perfect on my X4: the border is much closer to
the physical top side of the display than to the other sides. This might
be related to assembly variation during manufacturing, but it might as
well be related to the way a eink controller is connected to the display
(controller supports bigger display sizes, so an offset may be present).

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**NO**_

src/util/ScreenshotUtil.cpp

@@ -88,7 +88,12 @@ void ScreenshotUtil::takeScreenshot(GfxRenderer& renderer) {
 
   // Display a border around the screen to indicate a screenshot was taken
   if (renderer.storeBwBuffer()) {
-    renderer.drawRect(6, 6, renderer.getDisplayHeight() - 12, renderer.getDisplayWidth() - 12, 2, true);
+    int marginTop, marginRight, marginBottom, marginLeft;
+    renderer.getOrientedViewableTRBL(&marginTop, &marginRight, &marginBottom, &marginLeft);
+    int width = renderer.getScreenWidth() - marginLeft - marginRight - 1;
+    int height = renderer.getScreenHeight() - marginTop - marginBottom - 1;
+    // Add extra margin to the border to make it more visible
+    renderer.drawRect(marginLeft + 1, marginTop + 1, width - 2, height - 2, 2, true);
     renderer.displayBuffer();
     delay(1000);
     renderer.restoreBwBuffer();