feat: add type declarations

Author: anonrig

lib/index.d.ts

@@ -0,0 +1,4 @@
+declare namespace FastQuerystring {
+  export function stringify(value: string): Record<string, any>;
+  export function parse(value: Record<string, any>): string;
+}

package.json

@@ -4,6 +4,7 @@
   "description": "",
   "main": "lib/index.js",
   "type": "commonjs",
+  "types": "./lib/index.d.ts",
   "scripts": {
     "format": "rome format . --write",
     "format:ci": "rome format .",