feat: upgrade gradle

.idea/kotlinc.xml

@@ -8,6 +8,6 @@
   </component>
   <component name="KotlinJpsPluginSettings">
     <option name="externalSystemId" value="Gradle" />
-    <option name="version" value="2.3.21" />
+    <option name="version" value="2.4.20-RC" />
   </component>
 </project>

src/backend/gradle/wrapper/gradle-wrapper.properties

@@ -1,9 +1,6 @@
+#Mon Aug 17 12:30:11 UTC 2026
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://mirrors.cloud.tencent.com/gradle/gradle-9.6.1-bin.zip
-networkTimeout=10000
-retries=0
-retryBackOffMs=500
-validateDistributionUrl=true
+distributionUrl=https\://mirrors.cloud.tencent.com/gradle/gradle-9.7.0-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists