[DanielVdWP]

Description

Fixes #166.

When a custom variable is used both as a cube filter and as a
dimension, the generated detail URL may contain the same filter
condition twice.

This can cause incorrect results when navigating from a cube
to the corresponding host or service status view.

The issue affects both cube detail links and the actions used
to display matching hosts and services.

Changes

• Prevent duplicate equality conditions when generating cube
  detail URLs.
• Avoid adding redundant filters to host and service status
  action links.
• Preserve existing filters and dimension selections.
• Handle nested AND filters without incorrectly removing
  conditions inside OR expressions.
• Add automated regression tests covering host and service
  navigation.

Testing

Bug reproduction

The original implementation was tested using GitHub Actions
with PHP 8.3 and PHP 8.4.

Both environments reproduced the duplicate filter issue.

https://github.com/DanielVdWP/icingaweb2-module-cube/actions/runs/35562754291

Fix validation

After applying the fix, the regression tests passed on both
PHP versions.

The tests cover:

• Host and service detail URLs.
• Host and service status action links.
• Duplicate custom variable filters.
• Preservation of independent filter conditions.
• Nested AND filters and OR expressions.
• Preservation of distinct dimension selections.

The regression tests exercise the production URL-building code
with lightweight doubles for external dependencies.

The project's upstream PHP checks were also executed,
including linting, PHPUnit and PHPStan.

All 8 CI jobs completed successfully.

https://github.com/DanielVdWP/icingaweb2-module-cube/actions/runs/35562919130

Full end-to-end testing with a running Icinga Web 2 installation
has not been performed.