Add brightness option and run/dry wrapper scripts

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

treppe-run.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+# Usage: treppe-run.sh <shader.glsl> [brightness 0-100, default 100]
+set -euo pipefail
+here=$(dirname "$(realpath "$0")")
+[ $# -ge 1 ] || { echo "usage: $0 <shader.glsl> [brightness 0-100]" >&2; exit 2; }
+shader=$(realpath "$1")
+cd "$here"
+exec nix-shell --run "python treppe_gl.py '$shader' --brightness ${2:-100}"