docs: add hero image to README

Co-authored-by: Cursor <cursoragent@cursor.com>

README.md

@@ -3,14 +3,9 @@
 
 # Immich Frame
 
-An ESP32 firmware for the [M5Stack PaperColor](https://shop.m5stack.com/products/m5paper-color-esp32s3-dev-kit) e-ink display that turns it into a digital photo frame powered by your [Immich](https://immich.app/) server.
+![PaperColor displaying a photo from Immich](docs/PaperColor.jpg)
 
-<div align="center">
+An ESP32 firmware for the [M5Stack PaperColor](https://shop.m5stack.com/products/m5paper-color-esp32s3-dev-kit) e-ink display that turns it into a digital photo frame powered by your [Immich](https://immich.app/) server.
-  <figure>
-    <img src="docs/PaperColor.jpg" alt="PaperColor displaying a photo from Immich" width="400">
-    <figcaption><sub>PaperColor showing a dithered photo with location and date metadata overlays</sub></figcaption>
-  </figure>
-</div>
 
 ## Features