feat(health): add health check for Longhorn Volume

[yugstar]

What

Adds a health check for the longhorn.io/Volume CRD, which had no health check.

Behavior

Maps status.state + status.robustness:

• Degraded — robustness: faulted (data unavailable).
• Progressing — attached + robustness: degraded (rebuilding replicas), or a transitional state (creating/attaching/detaching/deleting).
• Healthy — attached + robustness: healthy, or cleanly detached (idle).

Values verified against the Longhorn v1beta2 API (VolumeRobustness healthy/degraded/faulted/unknown; VolumeState creating/attached/detached/attaching/detaching/deleting).

Tests

attached_healthy / detached / degraded / faulted / attaching fixtures; TestLuaHealthScript passes.

[bunnyshell]

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[codecov]

Bundle Report

Bundle size has no change ✅

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.22%. Comparing base (0b9298c) to head (a2acfe8).
⚠️ Report is 79 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #28662      +/-   ##
==========================================
+ Coverage   65.10%   65.22%   +0.11%     
==========================================
  Files         426      426              
  Lines       59623    59736     +113     
==========================================
+ Hits        38818    38961     +143     
+ Misses      17228    17186      -42     
- Partials     3577     3589      +12     

Flag	Coverage Δ
e2e	26.77% <ø> (+0.01%)	⬆️
unit-tests	60.60% <ø> (+0.14%)	⬆️

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[reggie-k]

Thanks for the PR! Could you please provide real manifests exported from your cluster where Longhorn is installed for each of the health statuses, along with reference to Longhorn docs describing the statuses, if such docs exist?
https://argo-cd.readthedocs.io/en/latest/developer-guide/#contributing-to-argo-cd-custom-health-checks