Add shell.nix & editorconfig

.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = space
+indent_size = 2

shell.nix

@@ -0,0 +1,6 @@
+{pkgs ? import <nixpkgs> {}}:
+pkgs.mkShell {
+  packages = with pkgs; [
+    bun
+  ];
+}