Add Pomodoro Timer Feature

[swaparup36]

Add a Pomodoro timer to help students focus on studying.

Task:

• Create a new PomodoroTimer class
• Implement 25-minute work sessions and 5-minute breaks
• Add CLI command to start timer
• Show countdown in terminal
• Play sound or notification when session ends (optional)

Expected Usage:

python main.py pomodoro --sessions 4

[yuvc21]

i want to work in this issue

[xenonnn4w]

Thanks @yuvc21 !