fix(triggershell): resolve openrgb-hue via PATH instead of hardcoded venv

Avoids baking in a machine-specific absolute path, and fails with
install instructions if the binary isn't found.

scripts/openrgb-hue-apply.sh

@@ -1,4 +1,11 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-exec /home/valknar/Projekte/openrgb-hue/.venv/bin/openrgb-hue apply "$SCENE" "$@"
+if ! command -v openrgb-hue >/dev/null 2>&1; then
+  echo "error: 'openrgb-hue' was not found on PATH." >&2
+  echo "Install it with:" >&2
+  echo "  pip install --index-url https://dev.pivoine.art/api/packages/valknar/pypi/simple/ --extra-index-url https://pypi.org/simple openrgb-hue" >&2
+  exit 1
+fi
+
+exec openrgb-hue apply "$SCENE" "$@"