Fix UI screenshot paths to PNG and add side-by-side frame photo layout

Update ui-upload and ui-gallery image refs from .jpg to .png, reduce
display size with clickable links to full resolution, and replace single
frame photo with a two-image side-by-side layout ready for new photos.

Made-with: Cursor

Author: 8ix

README.md

@@ -17,8 +17,9 @@ InkyStream runs on a home server and gives e-ink photo frames a brain. A frame w
 The challenge is making photographs look good on a screen that can only display six or seven colours. InkyStream handles this automatically using dithering, an algorithm that uses patterns of dots to simulate tones and gradients the hardware can't natively show. Upload a photo, InkyStream processes it, and a correctly sized and dithered variant for each configured device is ready to serve.
 
 <p align="center">
-  <img src="docs/frame.jpg" alt="Pimoroni Inky Frame displaying a photograph" width="700"><br>
-  <em>A Pimoroni Inky Frame 7.3" displaying a dithered photograph, running on batteries with no cables.</em>
+  <img src="docs/frame-1.jpg" alt="Pimoroni Inky Frame displaying a photograph" width="340">
+  <img src="docs/frame-2.jpg" alt="Pimoroni Inky Frame displaying a photograph" width="340"><br>
+  <em>Pimoroni Inky Frame 7.3" displays running on batteries with no cables.</em>
 </p>
 
 **Features:**
@@ -51,7 +52,7 @@ Go to the Devices tab and create a new device. Give it a name, select the displa
 Go to the Upload tab. Drag and drop photos or browse to select them. Assign each upload to a category, choose a dithering algorithm (Floyd-Steinberg works well for most images), and select which devices to process for. InkyStream handles the rest — resizing, dithering, and saving a processed variant for each device.
 
 <p align="center">
-  <img src="docs/ui-upload.jpg" alt="The InkyStream upload screen" width="700"><br>
+  <a href="docs/ui-upload.png"><img src="docs/ui-upload.png" alt="The InkyStream upload screen" width="500"></a><br>
   <em>The upload screen. Photos are processed and dithered automatically on upload.</em>
 </p>
 
@@ -60,7 +61,7 @@ Go to the Upload tab. Drag and drop photos or browse to select them. Assign each
 The gallery shows all processed images organised by category. Each image displays a thumbnail of the dithered result. Images can be deleted or reprocessed for different devices from here.
 
 <p align="center">
-  <img src="docs/ui-gallery.jpg" alt="The InkyStream image gallery" width="700"><br>
+  <a href="docs/ui-gallery.png"><img src="docs/ui-gallery.png" alt="The InkyStream image gallery" width="500"></a><br>
   <em>The image gallery, showing processed variants organised by category.</em>
 </p>