chore: 移除多余依赖与PostCSS配置

删除@capacitor/share、@capacitor/status-bar、@capawesome/capacitor-file-picker、postcss及相关依赖，移除postcss.config.js，简化依赖树。README下载链接样式调整为纯文本列表，提升可维护性。

src/main.ts

@@ -1,19 +1,10 @@
 import { createApp } from 'vue'
 import { createPinia } from 'pinia'
 import piniaPluginPersistedstate from 'pinia-plugin-persistedstate'
-import { Capacitor } from '@capacitor/core'
-import { StatusBar, Style } from '@capacitor/status-bar'
 import './style.css'
 import App from './App.vue'
 import router from './router'
 
-// Android 设置状态栏
-if (Capacitor.isNativePlatform()) {
-  StatusBar.setBackgroundColor({ color: '#1a1a2e' })
-  StatusBar.setStyle({ style: Style.Dark })
-  StatusBar.setOverlaysWebView({ overlay: false })
-}
-
 const app = createApp(App)
 const pinia = createPinia()