Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@python/cuopt_server/cuopt_server/tests/test_file_path_validation.py`:
- Around line 22-74: Add tests in test_file_path_validation.py to cover the two
missing branches in webserver.validate_file_path: (1) the CUOPT_DATA_DIR-unset
path by clearing/unsetting settings.set_data_dir (or not calling it) and calling
validate_file_path to assert it raises the expected HTTPException/status and
message about CUOPT_DATA_DIR being unset; and (2) the "must be a regular file"
path by creating a non-regular target inside the data dir (e.g., a subdirectory
or FIFO) and calling validate_file_path on that name to assert it raises
HTTPException with the "regular file" (or similar) detail. Use the existing test
helpers and exception assertions (pytest.raises and exc_info.value.detail) and
reference validate_file_path and settings.set_data_dir so the new tests exercise
those branches.

In `@python/cuopt_server/cuopt_server/webserver.py`:
- Around line 216-220: The log call leaks the resolved internal filesystem path
via file_path; update the error logging in webserver.py so it does not include
file_path (use cuopt_data_file or a generic message instead) and ensure any
HTTPException detail or other logs never expose the resolved server path; locate
the check using file_path and cuopt_data_file and replace the
logging.error(f"File path '{file_path}'...") with a safe message that references
only cuopt_data_file or a non-path generic string.

---

Outside diff comments:
In `@python/cuopt_server/cuopt_server/webserver.py`:
- Around line 1047-1052: The code validates the pathname via
validate_file_path(cuopt_data_file) and then later enqueues only the string
(file_path), leaving a TOCTOU window if CUOPT_DATA_DIR is writable; fix by
opening the file immediately after validate_file_path (e.g., obtain a file
descriptor or read bytes) and pass that safe handle/data into the queue instead
of the filename, or if you must enqueue a path, re-resolve and re-run
validate_file_path at the actual open site (the worker that processes the queue,
i.e., where you currently handle lines ~1142-1154) and ensure you use openat
with the directory fd or verify inode/dev after open to prevent symlink/race
attacks.