Ability to use enforcer.skip without POM.

### Affected version

3.6.2

### Bug description

I found myself in a situation where I wanted to create a new code repository.
I have a script that creates a default structure with two files in the `.mvn` folder
One is `extensions.xml`
```xml

org.apache.maven.extensions
maven-enforcer-extension
3.6.2

```

The other is `enforcer-extension.xml`
```xml

(3.6.3,)


17

```

Next in my routine is to generate a project from an archetype
```
mvn archetype:generate -Denforcer.skip
```

And the enforcer extension throws an exception
```
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO]
[INFO] >>> archetype:3.4.1:generate (default-cli) > generate-sources @ standalone-pom >>>
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.164 s
[INFO] Finished at: 2025-10-10T10:14:24+02:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-enforcer-plugin:3.6.2:enforce (default-extension): Goal requires a project to execute but there is no POM in this directory (/tmp/extension). Please verify you invoked Maven from the correct directory. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MissingProjectException
```

For me this is a minor inconvenience, but I was wondering if this behavior is correct.

I suppose `enforcer.skip` would be a POM property, overwritten by the JVM config.

Reproduce the reported `mvn archetype:generate -Denforcer.skip` command with the `.mvn/extensions.xml` and `enforcer-extension.xml` files shown in the issue. Inspect how the enforcer extension handles a standalone project without a POM; done means the skip behavior is clearly defined and the command no longer fails unexpectedly if skipping is supported.

Written by the indexing model from the issue text.