Replacing dual tracking with Accessibility-Only approach

We're transitioning from the current dual-tracking system (Usage Stats + Accessibility) to a more reliable and efficient Accessibility Service-only setup for tracking app usage and enforcing restrictions.

📌  Kindly refrain from creating new enhancement issues .

For more details, refer to the PR:
🔗 https://github.com/akaMrNagar/Mindful/pull/200