Fix libgpiod package name for Debian Trixie

libgpiod2 was renamed to libgpiod3 in Trixie (soname bump).
Use libgpiod-dev + gpiod instead, which pulls the correct shared
library as a dependency and works across Bookworm and Trixie.

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

setup-pi.sh

@@ -90,7 +90,7 @@ install_system_deps() {
         python3-venv python3-pip python3-dev \
         gcc g++ make \
         libjpeg-dev zlib1g-dev \
-        libgpiod2 libgpiod-dev \
+        libgpiod-dev gpiod \
         nginx git vim
     print_success "System dependencies installed"
 }