build: make build.gradle Gradle 9 configuration-cache compatible

Paired with the Gradle 9.4.1 wrapper bump: make the root and
imgui-binding build scripts usable under Gradle 9's configuration
cache (the default for downstream consumers on Gradle 9+).

Three changes:

- build.gradle: replace Groovy 'git describe'.execute() with
  providers.exec (cache-aware external process API). Same for
  'git rev-parse HEAD' in the jar manifest block.

- imgui-binding/build.gradle: capture project.version.toString() into
  a local at configuration time, and pass that through the
  processResources filesMatching closure rather than letting the
  closure resolve `version` against the live Project model at
  execution time.

Without this, any downstream consumer running Gradle 9 with
configuration cache on (including `includeBuild` composite builds)
hits:

  - Starting an external process 'git describe --tags --always' during
    configuration time is unsupported.
  - Invocation of 'version' references a Gradle script object from a
    Groovy closure at execution time, which is unsupported with the
    configuration cache.

Verified: `./gradlew :imgui-binding:compileJava --configuration-cache`
now stores a configuration cache entry cleanly on Gradle 9.4.1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: phraktle

build.gradle

@@ -6,9 +6,21 @@ ext {
     lwjglVersion = '3.4.1'
 }
 
+// Gradle 9's configuration cache forbids starting external processes at
+// configuration time via Groovy's '...'.execute() (the cache can't know
+// if the result would be different next time). Use providers.exec, which
+// is cache-aware.
+def gitDescribeProvider = providers.exec {
+    commandLine 'git', 'describe', '--tags', '--always'
+}.standardOutput.asText.map { it.trim().startsWith('v') ? it.trim().substring(1) : it.trim() }.orElse('unknown')
+
+def gitRevProvider = providers.exec {
+    commandLine 'git', 'rev-parse', 'HEAD'
+}.standardOutput.asText.map { it.trim() }.orElse('unknown')
+
 allprojects {
     group = 'imgui-java'
-    version = 'git describe --tags --always'.execute().text.trim().substring(1)
+    version = gitDescribeProvider.get()
 
     repositories {
         mavenCentral()
@@ -23,13 +35,14 @@ allprojects {
 
             def jdkMetadata = tasks.withType(JavaCompile).find().javaCompiler.get().metadata
             def buildJdk = "${jdkMetadata.javaRuntimeVersion} (${jdkMetadata.vendor})".toString()
+            def buildRev = gitRevProvider.get()
 
             manifest {
                 attributes (
                         'Implementation-Title': project.name,
                         'Implementation-Version': project.version,
                         'Build-Timestamp': new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ").format(System.currentTimeMillis()),
-                        'Build-Revision': 'git rev-parse HEAD'.execute().text.trim(),
+                        'Build-Revision': buildRev,
                         'Build-Jdk': buildJdk,
                         'Source-Compatibility': tasks.withType(JavaCompile).find().sourceCompatibility,
                         'Target-Compatibility': tasks.withType(JavaCompile).find().targetCompatibility,

imgui-binding/build.gradle

@@ -51,10 +51,14 @@ jar {
     }
 }
 
+// Capture project.version at configuration time so the closure below does not
+// reference the Project model at execution time -- Gradle 9 configuration cache
+// requirement.
+def processVersion = project.version.toString()
 processResources {
     filesMatching('**/imgui-java.properties') {
         filter(ReplaceTokens, tokens: [
-                'version': version
+                'version': processVersion
         ])
     }
 }