Add treppe-gl shader renderer for treppe2000

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

shell.nix

@@ -0,0 +1,16 @@
+let
+  pkgs = import <nixpkgs> {};
+  py = pkgs.python3.withPackages (ps: with ps; [
+    moderngl
+    glfw
+    numpy
+    pytest
+  ]);
+in pkgs.mkShell {
+  buildInputs = [
+    py
+    pkgs.libGL
+    pkgs.glfw
+  ];
+  LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath [ pkgs.libGL pkgs.glfw pkgs.libglvnd ];
+}