fix: update manifest files and use 2026-06 eclipse repository

[unru006]

I have installed a fresh 2026-06 version of Eclipse and recognized that the plugin is sadly not installable anymore - errors appear. After finding the repo and trying to build it, I saw that the build is broken as well...

So, to solve build errors:

[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 01:42 min
[INFO] Finished at: 2026-06-29T09:35:12Z
[INFO] ------------------------------------------------------------------------
[ERROR] Cannot resolve dependencies of project com.hybris.hyeclipse:com.hybris.hyeclipse.hac:eclipse-plugin:22.9.0-SNAPSHOT
[ERROR] with context {osgi.os=linux, osgi.ws=gtk, org.eclipse.update.install.features=true, osgi.arch=x86_64, org.eclipse.update.install.sources=true}
[ERROR] Software being installed: com.hybris.hyeclipse.hac 22.9.0.qualifier
[ERROR] Missing requirement: com.hybris.hyeclipse.commons 22.9.0.202606290933 requires 'osgi.ee; (&(osgi.ee=JavaSE)(version=21))' but it could not be found
[ERROR] Cannot satisfy dependency: com.hybris.hyeclipse.hac 22.9.0.qualifier depends on: osgi.bundle; com.hybris.hyeclipse.commons 0.0.0: See log for details
[ERROR] -> [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/ResolverException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn -rf :com.hybris.hyeclipse.hac
Error: Process completed with exit code 1.

and make it installable in Eclipse IDE:

Cannot complete the install because one or more required items could not be found.
Software being installed: SAP Commerce Cloud - development tools for Eclipse 22.8.0.RELEASE (com.hybris.hyeclipse.feature.feature.group 22.8.0.RELEASE)
Missing requirement: Extgen 22.8.0.RELEASE (com.hybris.hyeclipse.extgen 22.8.0.RELEASE) requires 'osgi.bundle; org.apache.commons.io 0.0.0' but it could not be found
Cannot satisfy dependency:
From: SAP Commerce Cloud - development tools for Eclipse 22.8.0.RELEASE (com.hybris.hyeclipse.feature.feature.group 22.8.0.RELEASE)
To: org.eclipse.equinox.p2.iu; com.hybris.hyeclipse.extgen [22.8.0.RELEASE,22.8.0.RELEASE]

...we have to update MANIFEST files to use/require JavaSE-21 since the project has been upgraded to this version. Also we have to use the latest eclipse repository to resolve required packages correctly.