Add gradle9 module: Spring Boot 4 build migrated from Gradle 8 to Gradle 9

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Gth99spB1CzQmBFofXmU4Z

gradle9/after/gradle/libs.versions.toml

@@ -0,0 +1,11 @@
+[versions]
+spring-boot = "4.1.1"
+dependency-management = "1.1.7"
+
+[libraries]
+starter-webmvc = { module = "org.springframework.boot:spring-boot-starter-webmvc" }
+starter-webmvc-test = { module = "org.springframework.boot:spring-boot-starter-webmvc-test" }
+
+[plugins]
+spring-boot = { id = "org.springframework.boot", version.ref = "spring-boot" }
+dependency-management = { id = "io.spring.dependency-management", version.ref = "dependency-management" }

gradle9/after/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,9 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.8.0-bin.zip
+networkTimeout=10000
+retries=0
+retryBackOffMs=500
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists