Title: .gitignore: app appends duplicate `.alma-snapshots` entry without checking existing patterns

Alma unconditionally appends .alma-snapshots to .gitignore every time it runs, without checking whether a matching pattern (e.g. **/.alma-snapshots/) already exists in the file. This results in duplicate entries and a perpetually dirty git status. Steps to reproduce: 1. Add **/.alma-snapshots/ (or any glob that already covers the path) to your .gitignore 2. Open/run Alma 3. Alma appends .alma-snapshots again at the end of the file 4. git diff now shows a new line added Expected: Alma should check if an existing pattern already matches .alma-snapshots before appending. A simple substring or line-by-line check would be sufficient. Workaround: Remove the original pattern and let Alma manage its own .alma-snapshots entry. Alma version: 0.0.790, macOS