check-buildplan: fail flag overwritten by checkVersionRangeInDependencies

The `fail` flag in `CheckBuildPlanMojo.execute()` is overwritten at the end, defeating the fail-fast check for non-reproducible plugins.

In `CheckBuildPlanMojo.java`:
- `fail` is set to `true` when a `fail:` (line 145) or too-old plugin (line 158) is found.
- Line 173 then unconditionally clobbers it:

```java
fail = checkVersionRangeInDependencies();
```

If the execution plan contains a non-reproducible plugin but the module has no version-range dependencies, the build will **not** fail even with `check.failOnNonReproducible=true`, silently ignoring the plugin issue.

Suggested fix: `fail = fail || checkVersionRangeInDependencies();`

Open CheckBuildPlanMojo.java and start in CheckBuildPlanMojo.execute(), tracing how fail is set before checkVersionRangeInDependencies(). Preserve an earlier failure while incorporating the dependency check result, then run the relevant project tests. Done means non-reproducible plugins still fail the build when check.failOnNonReproducible=true, including when no version-range dependencies exist.

Written by the indexing model from the issue text.