🛡️ Sentinel: [HIGH] Fix path traversal vulnerability in validate_path_within

[socialawy-dev]

🚨 Severity: HIGH
💡 Vulnerability: Path traversal validation via validate_path_within in src/audioformation/utils/security.py relied on string-based manipulation (os.path.abspath checking startswith). This approach is notoriously vulnerable to bypasses using crafted paths or complex symlink structures. Furthermore, the function lacked None handling, which could lead to unhandled AttributeError exceptions, causing server 500s or fail-open behavior in security checkpoints.
🎯 Impact: An attacker could potentially bypass the path traversal check to write or read arbitrary files outside of intended directories (e.g., project directories) if symlinks were involved or if string boundaries were manipulated.
🔧 Fix: Replaced the string-based check entirely with robust Path.resolve().is_relative_to() validation, delegating the symlink and bound resolution strictly to the OS. Explicitly added a path is None or root is None check. Expanded the exception handler to securely fail closed by returning False on TypeError and AttributeError.
✅ Verification: Run uv run pytest tests/ with the test suite. Ensure all tests still pass and no regressions exist in project/mix endpoints utilizing path resolution.

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PR created automatically by Jules for task 16901576811135188908 started by @socialawy

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[gemini-code-assist]

Code Review

This pull request refactors the validate_path_within utility to prevent path traversal bypasses by replacing string-based path comparisons with Path.resolve().is_relative_to() checks. It also introduces explicit null checks, expands exception handling for better robustness, and updates the security log and development dependencies. I have no feedback to provide.