fix: filter hidden files and directories from glob results in file_read

[xlyoung]

Problem

The search_file() function has two code paths:

1. os.walk path (for direct directory traversal) — correctly prunes hidden directories and skips hidden files
2. glob.glob path (for pattern matching) — no filtering, so files under .git/, .venv/, etc. appear in results

Fix

Add the same hidden file/directory filtering to glob results:

matching_files = [
    f for f in matching_files
    if not any(part.startswith(".") for part in f.split(os.sep) if part)
]

This checks every path component (not just the filename) to catch files nested under hidden directories.

Testing

All 18 file_read tests pass.

Fixes #289