Having one large, untracked file pegs single CPU core to ~100%

**Describe the bug**
Leaving stray ~700mb file in a repo results in `gitui` taking unreasonable amount of CPU time.

**To Reproduce**
Steps to reproduce the behavior:
1. Add random (very) large file to the git root.
2. Open `gitui`

**Expected behavior**
The file is ignored unless user explicitly adds it to the repository.

**Screenshots**
N/A

**Context (please complete the following information):**
- OS/Distro + Version: Debian 13
- GitUI Version: gitui 0.27.0 2025-01-14 (99f6967)
- Rust version: rustc 1.86.0 (05f9846f8 2025-03-31)

**Additional context**
Removing the file resolves the issue in its entirety.