pi: GPIO-controlled theme switch

- apt dependencies (RPI.GPIO somehow needs to be installed from apt to work & re-establish uv venv with --system-site-packages
- GPIO 20 triggers mode switching (can link to a photodiode or just switch)

scripts/deploy_backend.py

@@ -78,6 +78,23 @@ def deploy(restart: bool = False) -> bool:
         f"{ssh_target}:{remote_path}/",
     ])
 
+    # Ensure system GPIO package is installed (pip version needs compilation)
+    print()
+    print("Ensuring system GPIO package...")
+    run(
+        ["ssh", ssh_target, "dpkg -s python3-rpi.gpio >/dev/null 2>&1 || sudo apt install -y python3-rpi.gpio"],
+        check=False,
+    )
+
+    # Create venv with system-site-packages if it doesn't exist
+    # This allows access to apt-installed packages like python3-rpi.gpio
+    print()
+    print("Ensuring venv with system-site-packages...")
+    run(
+        ["ssh", ssh_target, f"cd {remote_path} && [ -d .venv ] || ~/.local/bin/uv venv --system-site-packages"],
+        check=False,
+    )
+
     # Run uv sync to install/update dependencies
     # Use full path since non-interactive SSH doesn't load .bashrc
     print()
@@ -115,9 +132,10 @@ def deploy(restart: bool = False) -> bool:
         print("Or run this script with --restart flag")
 
     print()
-    print("Note: First-time setup on Pi requires uv to be installed:")
+    print("Note: First-time setup on Pi requires:")
     print(f"  ssh {ssh_target}")
-    print("  curl -LsSf https://astral.sh/uv/install.sh | sh")
+    print("  curl -LsSf https://astral.sh/uv/install.sh | sh  # Install uv")
+    print("  sudo apt install python3-rpi.gpio                 # GPIO support")
 
     return True
 

scripts/pi_setup_backend.sh

@@ -27,10 +27,10 @@ else
     echo "uv already installed: $(uv --version)"
 fi
 
-# Install gpsd
-echo "Installing gpsd..."
+# Install gpsd and GPIO support
+echo "Installing system packages..."
 sudo apt-get update
-sudo apt-get install -y gpsd gpsd-clients
+sudo apt-get install -y gpsd gpsd-clients python3-rpi.gpio
 
 # Configure gpsd (user needs to edit DEVICES)
 GPSD_CONFIG="/etc/default/gpsd"
@@ -66,7 +66,10 @@ echo ""
 echo "Next steps:"
 echo "1. Configure gpsd: sudo nano /etc/default/gpsd"
 echo "2. Deploy backend: python3 scripts/deploy_backend.py (from dev machine)"
-echo "3. On Pi, install deps: cd $BACKEND_DIR && uv sync"
+echo "3. On Pi, create venv and install deps:"
+echo "     cd $BACKEND_DIR"
+echo "     uv venv --system-site-packages  # Allows access to apt packages"
+echo "     uv sync"
 echo "4. Start service: sudo systemctl start smartserow-backend"
 echo ""
 echo "Useful commands:"