Add Gradle wrapper (required for CI)

CI runs ./gradlew but the wrapper was never committed.
Gradle 8.10, matching the JDK 17 requirement.

https://claude.ai/code/session_015LpmjAt17XD582hZ9TPLCv

Author: claude

review-plugin/gradle/wrapper/gradle-wrapper.jar

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.10-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists