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

[thirdeyenation]

🚨 Severity: CRITICAL
💡 Vulnerability: Path traversal vulnerability in API endpoint api/api_files_get.py. The paths array allowed retrieving arbitrary files outside of the intended directories by injecting traversal sequences (../).
🎯 Impact: An attacker could read sensitive system files (e.g., /etc/passwd) or application source code, leading to severe information disclosure.
🔧 Fix: Implemented an explicit boundary check using files.is_in_base_dir(external_path) to ensure the resolved absolute path remains strictly within the intended base directory before attempting to read the file.
✅ Verification: Executed test cases providing paths with traversal sequences, confirming they are now rejected and returning empty results. Verified with pytest tests/test_image_get_security.py to ensure no regressions.

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PR created automatically by Jules for task 10084314743848165436 started by @thirdeyenation

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