fix: correct waveshare_epd import path

Was importing 'waveshare_epd' as a top-level package, but it's nested
under display/waveshare_epd/ -- caused ModuleNotFoundError on the Pi
since only display/ is on sys.path via main.py's imports, not
display/waveshare_epd/ itself. Verified the corrected import resolves
by exercising it directly; the only error left is the driver's own
platform check falling through to its Jetson Nano path on this non-Pi
dev machine, which is expected here and won't happen on the real
Raspberry Pi (it checks /proc/cpuinfo for "Raspberry").

display/epd4in0e_driver.py

@@ -22,7 +22,7 @@ class EPD4in0eDisplay(Display):
         self._epd = None
 
     def init(self) -> None:
-        from waveshare_epd import epd4in0e
+        from display.waveshare_epd import epd4in0e
 
         self._epd = epd4in0e.EPD()
         self._epd.init()