chore: centralize version management and upgrade Gradle to 9.1.0

Extract hardcoded plugin and dependency versions from build.gradle to gradle.properties for easier maintenance and updates. Upgrade Gradle wrapper from 8.14 to 9.1.0.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: pacphi

build.gradle

@@ -1,11 +1,11 @@
 plugins {
 	id 'java'
-	id 'com.vaadin' version '24.9.0'
-	id 'org.cyclonedx.bom' version '2.4.1'
-	id 'com.gorylenko.gradle-git-properties' version '2.5.3'
-	id 'org.springframework.boot' version '3.5.6'
-	id 'io.spring.dependency-management' version '1.1.7'
-	id 'org.eclipse.jkube.kubernetes' version '1.18.1'
+	id 'com.vaadin' version "${vaadinVersion}"
+	id 'org.cyclonedx.bom' version "${cyclonedxVersion}"
+	id 'com.gorylenko.gradle-git-properties' version "${gradleGitPropertiesVersion}"
+	id 'org.springframework.boot' version "${springBootVersion}"
+	id 'io.spring.dependency-management' version "${springDependencyManagementVersion}"
+	id 'org.eclipse.jkube.kubernetes' version "${jkubeVersion}"
 }
 
 group = 'org.cftoolsuite'
@@ -21,24 +21,19 @@ repositories {
 	maven { url 'https://maven.vaadin.com/vaadin-addons/' }
 }
 
-ext {
-	set('springCloudVersion', "2025.0.0")
-	set('vaadinVersion', "24.9.0")
-}
-
 dependencies {
 	implementation 'org.springframework.boot:spring-boot-starter-actuator'
 	implementation 'org.springframework.boot:spring-boot-starter-webflux'
 	implementation 'org.springframework.cloud:spring-cloud-starter-openfeign'
-	implementation 'org.apache.commons:commons-collections4:4.5.0'
-	implementation 'com.github.ben-manes.caffeine:caffeine:3.2.2'
-	implementation 'io.github.openfeign:feign-hc5:13.6'
-	implementation 'com.playtika.reactivefeign:feign-reactor-spring-cloud-starter:4.2.1'
+	implementation "org.apache.commons:commons-collections4:${commonsCollections4Version}"
+	implementation "com.github.ben-manes.caffeine:caffeine:${caffeineVersion}"
+	implementation "io.github.openfeign:feign-hc5:${feignHc5Version}"
+	implementation "com.playtika.reactivefeign:feign-reactor-spring-cloud-starter:${feignReactorVersion}"
 	implementation 'com.vaadin:vaadin-spring-boot-starter'
-	implementation 'org.vaadin.olli:file-download-wrapper:7.1.0'
+	implementation "org.vaadin.olli:file-download-wrapper:${fileDownloadWrapperVersion}"
 	implementation 'org.apache.commons:commons-lang3'
-	implementation 'io.pivotal.cfenv:java-cfenv-all:3.5.0'
-	implementation 'org.springframework.cloud:spring-cloud-bindings:2.0.4'
+	implementation "io.pivotal.cfenv:java-cfenv-all:${cfenvVersion}"
+	implementation "org.springframework.cloud:spring-cloud-bindings:${springCloudBindingsVersion}"
 	testImplementation 'org.springframework.boot:spring-boot-starter-test'
 	testImplementation 'io.projectreactor:reactor-test'
 	testRuntimeOnly 'org.junit.platform:junit-platform-launcher'

gradle.properties

@@ -1,3 +1,23 @@
+# Gradle memory management
 org.gradle.jvmargs=-Xmx4096m
+
+# Artifact version
 version=0.0.1-SNAPSHOT
 
+# Plugin versions
+vaadinVersion=24.9.0
+cyclonedxVersion=2.4.1
+gradleGitPropertiesVersion=2.5.3
+springBootVersion=3.5.6
+springDependencyManagementVersion=1.1.7
+jkubeVersion=1.18.1
+
+# Dependency versions
+springCloudVersion=2025.0.0
+commonsCollections4Version=4.5.0
+caffeineVersion=3.2.2
+feignHc5Version=13.6
+feignReactorVersion=4.2.1
+fileDownloadWrapperVersion=7.1.0
+cfenvVersion=3.5.0
+springCloudBindingsVersion=2.0.4

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.1.0-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME