Upgrade Gradle wrapper from 7.6 to 8.14.3 for JDK 21 support

The CI JDK was upgraded from 17 to 21, but Gradle 7.6 only supports
running on JDK up to 19. Running it on JDK 21 made the Groovy script
compiler reject the JDK-21 (class file major version 65) settings.gradle
with 'Unsupported class file major version 65' / 'Could not open settings
generic class cache'. Gradle 8.5 is the first release to support JDK 21;
8.14.3 is the latest 8.x (supports JDK 21-24) and avoids the breaking
changes of the 9.x line. Verified locally: 'gradlew help' configures the
:mobile Android project BUILD SUCCESSFUL under JDK 21.

Assisted-By: Claude Opus 4.8

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.3-all.zip