🛡️ Sentinel: [CRITICAL/HIGH] Fix command injection in toolExists

[acebytes]

🚨 Severity: HIGH
💡 Vulnerability: Command Injection in toolExists within Sources/Cacheout/Models/CacheCategory.swift. The function used string interpolation to inject the tool variable directly into a shell("/usr/bin/which \(tool)") wrapper.
🎯 Impact: If requiresTool is manipulated to contain spaces or shell metacharacters, it allows arbitrary command execution via /bin/bash -c.
🔧 Fix: Replaced the insecure shell wrapper with a direct Foundation.Process execution. The command /usr/bin/env which is now invoked with arguments safely segregated from the executable path, neutralizing the injection point.
✅ Verification: Swift code compiles, and testing on environment indicates secure parsing. Test suite script cannot run natively on the current container. Added learning to .jules/sentinel.md journal.

---

PR created automatically by Jules for task 16882059175438663628 started by @acebytes

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.