ux(provisioning): portrait arrow points right, not up

In portrait orientation the cable/ribbon is on the left, so the
physical 'up' edge of the hung frame corresponds to the right side
of the rendered diagram — not the top. Swap the up-arrow inside the
portrait screen for a right-arrow so the diagram actually shows the
user which edge will be up when they hang the frame.

Landscape diagram is unchanged (cable on bottom → up is up).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/gen_screens.py

@@ -118,6 +118,19 @@ def up_arrow(draw, cx, cy, half_w=12, h=22, color=BK):
     ], fill=color)
 
 
+def right_arrow(draw, cx, cy, half_h=12, w=22, color=BK):
+    """Solid filled triangle pointing right, centered on (cx, cy).
+
+    Used in the portrait diagram: with the cable/ribbon on the left,
+    the physical 'up' edge of the frame (when hung) is the right side
+    of the rendered diagram, so the arrow points that way."""
+    draw.polygon([
+        (cx + w // 2,  cy),            # tip
+        (cx - w // 2,  cy - half_h),   # base top
+        (cx - w // 2,  cy + half_h),   # base bottom
+    ], fill=color)
+
+
 def orientation_diagrams(draw, accent, show_active_ls=True):
     """Draw both orientation diagrams in the centre panel.
 
@@ -159,7 +172,7 @@ def orientation_diagrams(draw, accent, show_active_ls=True):
     draw.rectangle([pt_x-pr_w, pt_y, pt_x-1, pt_y+pr_h-1], fill=BK)
     draw.rectangle([pt_x, pt_y, pt_x+pt_w-1, pt_y+pt_h-1], outline=BK, width=3)
 
-    up_arrow(draw, pt_x + pt_w // 2, pt_y + pt_h // 2, half_w=12, h=22)
+    right_arrow(draw, pt_x + pt_w // 2, pt_y + pt_h // 2, half_h=12, w=22)
 
 
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