Add sillytavern nix shell

nix-shells/sillytavern.nix

@@ -0,0 +1,17 @@
+# SillyTavern - Ai/LLMs WebUI
+let
+  nixpkgs = fetchTarball "https://github.com/NixOS/nixpkgs/tarball/master";
+  pkgs = import nixpkgs { config = {}; overlays = []; };
+in
+
+pkgs.mkShellNoCC {
+  packages = with pkgs; [
+    nodejs
+    nodePackages.typescript-language-server
+  ];
+
+  # Startup command
+  shellHook = ''
+    ./start.sh
+  '';
+}