feat: add weapp-tailwindcss integration for uni-app

Install required dependencies, configure PostCSS and Vite plugin, create global app.css entry file, import styles in main.js, and add postinstall patch script.

src/app.css

@@ -0,0 +1,7 @@
+@import "weapp-tailwindcss/index.css";
+
+@source "./**/*.{vue,js,ts}";
+@source not "./uni_modules";
+@source not "../dist";
+@source not "../node_modules";
+@source not "../docs";

src/main.js

@@ -1,4 +1,5 @@
 import App from "./App";
+import "./app.css";
 import share from "./utils/share";
 
 // #ifndef VUE3
@@ -32,4 +33,4 @@ export function createApp() {
     pinia,
   };
 }
-// #endif
+// #endif