Backend

How path traversal happens in Python open() and how to fix it

A high-severity path traversal vulnerability was discovered in `src/backend/snitch.py` where the `writeTestcase()` function accepted a user-controlled `portDir` parameter without sanitization. An attacker could craft malicious input like `../../etc` to write files outside the intended output directory. The fix implements path canonicalization using `pathlib.Path.resolve()` and validates that the final destination stays within the allowed base directory.