build(gradle): upgrade Gradle wrapper to 9.6.1

Align wrapper with Gradle 9.6.1 distribution.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: cristianrcv

gradle/wrapper/gradle-wrapper.jar

@@ -1,7 +1,9 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-9.3.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.6.1-bin.zip
 networkTimeout=10000
+retries=0
+retryBackOffMs=500
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists