ead: 🛡️ Sentinel: [CRITICAL] Fix command injection

[ManupaKDU]

🚨 Severity: CRITICAL
💡 Vulnerability: Command injection in ead via system() function
🎯 Impact: Arbitrary shell command execution by manipulating shell operators
🔧 Fix: Replaced system() with execvp() and added string tokenizer
✅ Verification: Built ead locally with make

Signed-off-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

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PR created automatically by Jules for task 9598384465612103451 started by @manupawickramasinghe

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