App does not handle corrupted JSON file gracefully

[angjozee]

Steps:

Open data/addressbook.json

Delete a quote or comma

Screenshot 2025-04-04 at 4.37.17 PM

Save and relaunch MediBook
Expected: App shows a warning or offers to load backup/sample data
Actual: App resets to empty state silently / crashes

Screenshot 2025-04-04 at 4.38.12 PM