Expose response body digest for unexpected status codes

### New feature, improvement proposal

Codes like a 403 usually don't say much without having access to the response body.
Central seems to use this to indicate blocking of certain client IPs (https://the-asf.slack.com/archives/C7Q9JB404/p1776682107010189). In order to ease debugging issues like this the response body should be exposed (at least partially) in the exception.

Example stack trace:

```
Caused by: org.eclipse.aether.transfer.ArtifactTransferException: Could not transfer artifact eu.maveniverse.maven.mimir:extension3:pom:0.11.3 from/to central (https://repo.maven.apache.org/maven2): HTTP Status: 403
at org.eclipse.aether.connector.basic.ArtifactTransportListener.transferFailed(ArtifactTransportListener.java:44)
at org.eclipse.aether.connector.basic.BasicRepositoryConnector$TaskRunner.run(BasicRepositoryConnector.java:467)
at org.eclipse.aether.connector.basic.BasicRepositoryConnector.get(BasicRepositoryConnector.java:290)
at org.eclipse.aether.internal.impl.filter.FilteringRepositoryConnector.get(FilteringRepositoryConnector.java:95)
at org.eclipse.aether.internal.impl.offline.OfflineRepositoryConnector.get(OfflineRepositoryConnector.java:82)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:503)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:400)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:201)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:180)
at org.apache.maven.impl.resolver.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:173)
at org.apache.maven.impl.resolver.DefaultArtifactDescriptorReader.readArtifactDescriptor(DefaultArtifactDescriptorReader.java:121)
at org.eclipse.aether.internal.impl.DefaultRepositorySystem.readArtifactDescriptor(DefaultRepositorySystem.java:206)
at org.apache.maven.plugin.internal.DefaultPluginDependenciesResolver.resolveCoreExtension(DefaultPluginDependenciesResolver.java:173)
at org.apache.maven.cling.extensions.BootstrapCoreExtensionManager.resolveExtension(BootstrapCoreExtensionManager.java:230)
at org.apache.maven.cling.extensions.BootstrapCoreExtensionManager.resolveCoreExtensions(BootstrapCoreExtensionManager.java:167)
at org.apache.maven.cling.extensions.BootstrapCoreExtensionManager.loadCoreExtensions(BootstrapCoreExtensionManager.java:150)
at org.apache.maven.cling.invoker.PlexusContainerCapsuleFactory.loadCoreExtensions(PlexusContainerCapsuleFactory.java:304)
at org.apache.maven.cling.invoker.PlexusContainerCapsuleFactory.container(PlexusContainerCapsuleFactory.java:90)
at org.apache.maven.cling.invoker.PlexusContainerCapsuleFactory.createContainerCapsule(PlexusContainerCapsuleFactory.java:81)
at org.apache.maven.cling.invoker.LookupInvoker.container(LookupInvoker.java:517)
at org.apache.maven.cling.invoker.LookupInvoker.doInvoke(LookupInvoker.java:158)
at org.apache.maven.cling.invoker.LookupInvoker.invoke(LookupInvoker.java:134)
at org.apache.maven.cling.ClingSupport.run(ClingSupport.java:76)
at org.apache.maven.cling.MavenCling.main(MavenCling.java:51)
at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.lang.reflect.Method.invoke(Method.java:565)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:255)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:201)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:361)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:314)
Caused by: org.eclipse.aether.spi.connector.transport.http.HttpTransporterException: HTTP Status: 403
at org.eclipse.aether.transport.jdk.JdkTransporter.lambda$implGet$0(JdkTransporter.java:301)
at org.eclipse.aether.spi.connector.transport.http.RFC9457.RFC9457Reporter.generateException(RFC9457Reporter.java:75)
at org.eclipse.aether.transport.jdk.JdkTransporter.implGet(JdkTransporter.java:300)
at org.eclipse.aether.spi.connector.transport.AbstractTransporter.get(AbstractTransporter.java:64)
at org.eclipse.aether.connector.basic.BasicRepositoryConnector$GetTaskRunner.runTask(BasicRepositoryConnector.java:533)
at org.eclipse.aether.connector.basic.BasicRepositoryConnector$TaskRunner.run(BasicRepositoryConnector.java:464)
at org.eclipse.aether.connector.basic.BasicRepositoryConnector.get(BasicRepositoryConnector.java:290)
at org.eclipse.aether.internal.impl.filter.FilteringRepositoryConnector.get(FilteringRepositoryConnector.java:95)
at org.eclipse.aether.internal.impl.offline.OfflineRepositoryConnector.get(OfflineRepositoryConnector.java:82)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:503)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:400)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:201)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:180)
at org.apache.maven.impl.resolver.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:173)
at org.apache.maven.impl.resolver.DefaultArtifactDescriptorReader.readArtifactDescriptor(DefaultArtifactDescriptorReader.java:121)
at org.eclipse.aether.internal.impl.DefaultRepositorySystem.readArtifactDescriptor(DefaultRepositorySystem.java:206)
at org.apache.maven.plugin.internal.DefaultPluginDependenciesResolver.resolveCoreExtension(DefaultPluginDependenciesResolver.java:173)
at org.apache.maven.cling.extensions.BootstrapCoreExtensionManager.resolveExtension(BootstrapCoreExtensionManager.java:230)
at org.apache.maven.cling.extensions.BootstrapCoreExtensionManager.resolveCoreExtensions(BootstrapCoreExtensionManager.java:167)
at org.apache.maven.cling.extensions.BootstrapCoreExtensionManager.loadCoreExtensions(BootstrapCoreExtensionManager.java:150)
at org.apache.maven.cling.invoker.PlexusContainerCapsuleFactory.loadCoreExtensions(PlexusContainerCapsuleFactory.java:304)
at org.apache.maven.cling.invoker.PlexusContainerCapsuleFactory.container(PlexusContainerCapsuleFactory.java:90)
at org.apache.maven.cling.invoker.PlexusContainerCapsuleFactory.createContainerCapsule(PlexusContainerCapsuleFactory.java:81)
at org.apache.maven.cling.invoker.LookupInvoker.container(LookupInvoker.java:517)
at org.apache.maven.cling.invoker.LookupInvoker.doInvoke(LookupInvoker.java:158)
at org.apache.maven.cling.invoker.LookupInvoker.invoke(LookupInvoker.java:134)
at org.apache.maven.cling.ClingSupport.run(ClingSupport.java:76)
at org.apache.maven.cling.MavenCling.main(MavenCling.java:51)
at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.lang.reflect.Method.invoke(Method.java:565)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:255)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:201)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:361)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:314)
```

Start at JdkTransporter.implGet and RFC9457Reporter.generateException, the entry points shown in the stack trace, and inspect how HTTP status exceptions are constructed. Done means unexpected-status exceptions expose at least part of the response body, with behavior covered by the relevant existing tests if present.

Written by the indexing model from the issue text.