fix: UTF-8 BOM+loadDataWithBaseURL(utf-8)修复乱码

- frame.html/index.html 添加 UTF-8 BOM (EF BB BF)
- loadDataWithBaseURL 显式设置 utf-8 编码
- WebView 以此识别中文内容

packages/client-android/android/app/src/main/java/dev/yuzu/gca/MainActivity.kt

@@ -25,8 +25,9 @@ class MainActivity : AppCompatActivity() {
                 loadDataWithBaseURL("file:///android_asset/", html, "text/html", "UTF-8", null)
                 Log.i(TAG, "Loaded cached HTML (${cacheFile.length()}B)")
             } else {
-                loadUrl("file:///android_asset/frame.html")
-                Log.i(TAG, "Loaded frame.html")
+                val html = assets.open("frame.html").bufferedReader().readText()
+                loadDataWithBaseURL("file:///android_asset/", html, "text/html", "utf-8", null)
+                Log.i(TAG, "Loaded frame.html (${html.length}B)")
             }
         }
         setContentView(wv)