🛡️ Sentinel: [security improvement] Remove shell wrapper for docker prune execution

[acebytes]

🎯 What: Removed the usage of /bin/bash -c to execute docker system prune within CacheoutViewModel.swift.

⚠️ Risk: Execution of processes via shell wrappers is a systemic risk that can introduce command injection vulnerabilities if arbitrary strings are ever interpolated into the command. While this specific instance did not have dynamic interpolation, relying on /bin/bash violates the principle of least privilege and increases the attack surface.

🛡️ Solution: Replaced the /bin/bash -c wrapper with a direct invocation of /usr/bin/env executing docker with an explicit array of arguments. The shell redirection operator 2>&1 was securely replicated in Swift by assigning the same Pipe() instance to both process.standardOutput and process.standardError. A journal entry detailing this learning was also added to .jules/sentinel.md.

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PR created automatically by Jules for task 17466590518007831702 started by @acebytes

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