feat: 引入 Conscrypt 解决 Android 8.1 TLS 握手失败

设备系统 conscrypt 版本过旧，连阿里云 OSS 的 HTTPS 握手被 reset。
引入 org.conscrypt:conscrypt-android:2.5.2 作为首选安全提供者，
在 Application.onCreate 中注册，所有网络请求自动使用现代 TLS。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gradle/libs.versions.toml

@@ -13,6 +13,7 @@ gson = "2.10.1"
 paho = "1.2.5"
 timber = "5.0.1"
 zxing = "3.5.3"
+conscrypt = "2.5.2"
 swiperefresh = "1.1.0"
 viewpager2 = "1.0.0"
 coreKtx = "1.12.0"
@@ -73,6 +74,9 @@ paho-mqtt = { group = "org.eclipse.paho", name = "org.eclipse.paho.client.mqttv3
 # Logging
 timber = { group = "com.jakewharton.timber", name = "timber", version.ref = "timber" }
 
+# TLS (解决 Android 8.1 设备 HTTPS 握手兼容问题)
+conscrypt = { group = "org.conscrypt", name = "conscrypt-android", version.ref = "conscrypt" }
+
 # QR Code
 zxing-core = { group = "com.google.zxing", name = "core", version.ref = "zxing" }