chore: 清理gradle废弃配置，移除enableJetifier

- 移除已废弃的enableJetifier=true
- 添加generateSyncIssueWhenLibraryConstraintsAreEnabled抑制重复警告
- 其余deprecated属性暂保留（删除会导致构建失败）

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

android-app/gradle.properties

@@ -1,7 +1,6 @@
 # Project-wide Gradle settings
 org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
 android.useAndroidX=true
-android.enableJetifier=true
 android.defaults.buildfeatures.resvalues=true
 android.sdk.defaultTargetSdkToCompileSdkIfUnset=false
 android.enableAppCompileTimeRClass=false
@@ -12,3 +11,4 @@ android.r8.strictFullModeForKeepRules=false
 android.r8.optimizedResourceShrinking=false
 android.builtInKotlin=false
 android.newDsl=false
+android.generateSyncIssueWhenLibraryConstraintsAreEnabled=false