style: init .editorconfig

.editorconfig

@@ -0,0 +1,15 @@
+# editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+indent_size = 2
+
+# TypeScript and JavaScript files
+[*.{ts,tsx,js,jsx}]
+indent_size = 2
+quote_type = single