🛡️ Sentinel: [HIGH] Fix path traversal boundary check bypass in Lua IO module

[mleem97]

🚨 Severity: HIGH

💡 Vulnerability: The ResolveSafe function in GregIoLuaModule.cs attempted to sandbox file access to the mod's data directory using fullPath.StartsWith(dataDirFull). Because it did not ensure dataDirFull ended with a directory separator, an attacker could access a directory outside the sandbox if its name began with the sandbox's directory name (e.g., breaking out of /mods/modA/data by targeting /mods/modA/data_secret/file.txt).

🎯 Impact: Malicious Lua mods could exploit this boundary check bypass to read, write, or delete sensitive files residing in maliciously similarly named directories outside their intended sandbox, leading to potential unauthorized data access or corruption.

🔧 Fix: Updated the StartsWith boundary check to append Path.DirectorySeparatorChar to the sandbox directory path before validation, while also permitting an exact string match in case the mod legitimately references the base directory itself.

✅ Verification: The codebase has been locally patched, verified via manual inspection, and the core test suite has been successfully re-run.

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PR created automatically by Jules for task 2063171553300936068 started by @mleem97

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