Improve Input Validation and UX for Adding Tasks

Currently, the To-Do-List app allows users to add empty or whitespace-only tasks, which affects usability and clarity.

💡 Expected Behavior:

The app should prevent adding empty tasks.

If the user clicks “Add” with no input, show a short, clear message like:

⚠️ Please enter a task before adding.

Optionally, disable the “Add” button until input is non-empty.

(Bonus) Add a character limit (e.g., 100 chars) with a small counter or visual feedback.