Run service as root for NeoPixel DMA access

The rpi_ws281x library needs /dev/mem for DMA-based LED control, which
requires root. Any service restart was causing a SEGV crash loop
because the process ran as a regular user.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dune-weaver.service

@@ -4,7 +4,7 @@ After=network.target
 
 [Service]
 Type=simple
-User=USER_PLACEHOLDER
+User=root
 WorkingDirectory=INSTALL_DIR_PLACEHOLDER
 ExecStart=INSTALL_DIR_PLACEHOLDER/.venv/bin/python INSTALL_DIR_PLACEHOLDER/main.py
 Restart=always