🛡️ Sentinel: [CRITICAL] Fix path traversal in zip extraction

[thirdeyenation]

🚨 Severity: CRITICAL
💡 Vulnerability: Path traversal / Zip Slip vulnerability in helpers/skills_import.py zip extraction.
🎯 Impact: An attacker could overwrite arbitrary files on the system outside the designated extraction directory if they supply a maliciously crafted zip file.
🔧 Fix: Validated all zip archive members against the target extraction directory before calling extractall().
✅ Verification: Ran a temporary Python script to assert a ValueError is raised on unsafe paths like ../unsafe.txt.

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PR created automatically by Jules for task 8901489086939724182 started by @thirdeyenation

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