fix: defer compile-classpath probes out of GroovyCompile task configuration

[codeconsole]

Problem

On Gradle 9.5+, running a task that depends on compileClasspath without also depending on the compile task — e.g. asset-pipeline's assetCompile — fails during task-graph construction:

Could not determine the dependencies of task ':assetCompile'.
> Could not resolve all dependencies for configuration ':compileClasspath'.
   > Could not create task ':compileGroovy'.
      > Could not resolve all dependencies for configuration ':compileClasspath'.
         > Cannot observe dependencies before markAsObserved(String) has been called.

The chain (observed from a Grails 8.0.0-M4 app on Gradle 9.6.1):

1. Scheduling assetCompile resolves compileClasspath for build dependencies.
2. Mid-resolve, Gradle freezes the configuration's attributes; the target-JVM attribute's provider chain realizes the compileGroovy task.
3. Task realization fires GrailsGradlePlugin.configureGroovyCompiler's configureEach callback, which calls getGroovyCompilerScript → isClassOnClasspath(compile.classpath, …) → classpath.files — re-entering the resolution already in flight.
4. Gradle 9.5+'s stricter resolution state machine rejects the re-entrancy with the markAsObserved IllegalStateException. Older Gradle (9.4.x and below) tolerated it silently.

Invocations that realize the compile tasks during task selection (build, compileGroovy, or even assetCompile compileGroovy) are unaffected, which makes the failure look sporadic.

Fix

Move the star-import computation — including the two isClassOnClasspath classpath probes — inside the closure that getGroovyCompilerScript returns. That closure is only invoked from the task's doFirst, at execution time, where resolving the classpath is legal. Nothing at task-configuration time touches the classpath anymore.

The GrailsPluginGradlePlugin override already invokes the parent closure lazily inside its own closure (parent?.call() ?: ''), so it composes unchanged, and the call site's existing null handling covers the no-imports case.

Verification

• :grails-gradle-plugins:compileGroovy passes.
• Published the patched plugin locally and pointed the affected Grails 8.0.0-M4 app at it: ./gradlew assetCompile now constructs its task graph and runs (previously failed as above), and the generated grailsGroovyCompilerConfig-compileGroovy.groovy still contains all three star-import packages (jakarta.validation.constraints, grails.gorm.annotation, grails.plugin.scaffolding.annotation), confirming the deferred probes see the same classpath. Full app compile succeeds with the auto-imports in effect.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.8562%. Comparing base (57883c4) to head (4fdb88b).

Files with missing lines	Patch %	Lines
...rails/gradle/plugin/core/GrailsGradlePlugin.groovy	0.0000%	12 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##             8.0.x     #16076         +/-   ##
================================================
+ Coverage         0   51.8562%   +51.8562%     
- Complexity       0      18110      +18110     
================================================
  Files            0       2046       +2046     
  Lines            0      96274      +96274     
  Branches         0      16727      +16727     
================================================
+ Hits             0      49924      +49924     
- Misses           0      38980      +38980     
- Partials         0       7370       +7370     

Files with missing lines	Coverage Δ
...rails/gradle/plugin/core/GrailsGradlePlugin.groovy	0.0000% <0.0000%> (ø)

... and 2045 files with indirect coverage changes

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[testlens-app]

✅ All tests passed ✅

🏷️ Commit: 4fdb88b
▶️ Tests: 57599 executed
⚪️ Checks: 60/60 completed

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