Remove _hannio_splash startup bitmap from the BROSE9323 driver

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/nano/README.md

@@ -8,8 +8,8 @@ logic.
 
 ## Behaviour
 
-- **Boot:** the Nano flips the whole display on and then off, shows the splash bitmap and
-  prints the time a full redraw took.
+- **Boot:** the Nano flips the whole display on and then off, then prints the time a full
+  redraw took.
 - **`display()`:** compares the new buffer with the last one that was shown and strobes
   only the dots that changed.
 - **Every 2 minutes** (`REFRESH_TIME`) it forces a full redraw to fix dots that got stuck.