Fix: #259 Windows grep backslash handling in _grep

[wasiqnauman]

Summary

This fixes a Windows bug in code_puppy.tools.file_operations._grep where search strings containing backslashes were corrupted before being passed to ripgrep.

The root cause was POSIX shlex.split(search_string), which treats \ as an escape character. On Windows that broke common searches like \bhello\b, \d+, foo.bar, and path-like input such as C:\Users\me.

Changes

use Windows-safe argument splitting for _grep
preserve backslashes in regex and path-like input
surface ripgrep errors instead of silently returning zero matches
add regression tests for Windows backslash handling and ripgrep error propagation
Notes
grep is still regex-based by default. A raw search like C:\Users\me now returns the real ripgrep regex error instead of looking like “no matches”. For literal path searches, use -F "C:\Users\me".

Passed:

pytest tests/tools/test_file_operations_coverage.py -q
pytest tests/tools/test_file_operations_coverage.py -q -k grep

Manual Windows smoke test:

\bhello_world\b matched
\d+ matched
-F "C:\Users\me" matched literal Windows paths