🛡️ Sentinel: [CRITICAL] Fix Path Traversal in API Files Get

[thirdeyenation]

🚨 Severity: CRITICAL
💡 Vulnerability: The ApiFilesGet endpoint allowed arbitrary file reads (path traversal) by supplying absolute paths like /etc/passwd.
🎯 Impact: Attackers could read sensitive configuration files, secrets, or logs on the server.
🔧 Fix: Added files.is_in_base_dir(external_path) validation to ensure requested files are strictly within the application's base directory.
✅ Verification: Ran test script confirming that attempts to access /etc/passwd via both relative and absolute paths are blocked.

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PR created automatically by Jules for task 5030792423400181638 started by @thirdeyenation

[google-labs-jules]

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