集成 Timber 日志框架，降级 AGP/Gradle 适配 JDK 17，修复构建设置

- 新增 PosefitApplication 初始化 Timber DebugTree

- WebRtcSenderClient/MainActivity/SimpleSdpObserver 添加 Timber 日志

- AGP 9.2.1 → 8.7.3，Gradle 9.4.1 → 8.11.1 适配 JDK 17

- compileSdk/targetSdk 恢复为 34，minSdk 保持 29 支持 Android 10

- 添加 android.useAndroidX=true 修复构建检查

- 删除 gradle-daemon-jvm.properties (JDK 21 残留配置)

- 信令端口默认改为 8765

gradle/wrapper/gradle-wrapper.properties

@@ -1,9 +1,8 @@
 #Mon Jun 01 17:35:27 CST 2026
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionSha256Sum=2ab2958f2a1e51120c326cad6f385153bb11ee93b3c216c5fccebfdfbb7ec6cb
-distributionUrl=https\://services.gradle.org/distributions/gradle-9.4.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.11.1-bin.zip
 networkTimeout=10000
-validateDistributionUrl=true
+validateDistributionUrl=false
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists