1.2.0

Optional aspect ratio normalization for OG images.

• ?ratio=3:2 pads GitHub OG images to 3:2 (1200x800) with white top padding and stretched language bar at the bottom
• Also supports ?ratio=4:3
• Pure in-worker PNG manipulation, zero new dependencies
• Falls back to normal 302 redirect for non-PNG images or on any error
• Landing page adds a "Normalize Aspect Ratio" checkbox and pre-filled demo