🔧 Chore: change giscus dark theme and enable PWA

exampleSite/config.toml

@@ -536,7 +536,7 @@ enableEmoji = true
   images = ["/logo.png"]
   # enable PWA since v0.2.12
   # 开启 PWA 支持 since v0.2.12
-  enablePWA = false
+  enablePWA = true
   # whether to add external Icon for external links automatically since v0.2.14
   # 是否自动显示外链图标 since v0.2.14
   externalIcon = true
@@ -941,7 +941,7 @@ enableEmoji = true
         emitMetadata = "0"
         inputPosition = "bottom" # top, bottom
         lightTheme = "light"
-        darkTheme = "dark"
+        darkTheme = "dark_dimmed"
         lazyLoad = true
     # Third-party library config
     # 第三方库配置