[patch] Disable incompatible sitectl-isle formula

[libops-agent]

Summary

• disable sitectl-isle 0.19.0 because Homebrew cannot express its exact legacy core/Drupal dependency set
• add the missing formula description and MIT license metadata
• make the tap verifier reject any enabled pre-v1 ISLE formula, preventing an older reconciliation workflow from silently restoring the unsafe combination

The release assets remain available for the documented manual legacy installation. This only blocks Homebrew from resolving 0.19.0 alongside the v1 core formulas.

Validation

• 7 Ruby verifier tests / 19 assertions
• all four existing ISLE release assets and checksums verified
• brew audit --strict --formula (before policy addition; formula unchanged afterward)
• brew style (before policy addition)
• actual brew install refusal with the compatibility reason
• git diff --check