[Playtime session] Implement 'Stop' button functionality

[Rushi-faldu]

Purpose:

Add functionality to the 'Stop' button to exit the current activity and navigate to the home screen.

User Story:

As a user, I want the app to provide a 'Stop' button when the activity is in session so that I can end the activity at any time.

Acceptance Criteria:

• The 'Stop' button terminates the current activity session cleanly.
• Any ongoing voice input or AI instructions must stop upon pressing the button.
• Navigate to the home screen with no delay.

Other notes

Out of scope: Ensure user activity data (e.g., completed or skipped) is stored for feedback purposes. This will be discussed in the next meeting with IP.

Design notes

• Wireframes are here

• Design specifics are here

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Definition of Done (DoD)

• The feature has been fully implemented, thoroughly tested, and integrated into the app with no critical bugs or performance issues.
• Manual testing is complete, verifying that the feature meets all acceptance criteria.
• Big features are documented inside the code, with clear explanations of functionality, usage, and any relevant edge cases.
• The feature has undergone peer review, with the code approved by at least one other team member to ensure quality and maintainability.
• The feature branch has been successfully merged into the main branch, and the pull request is closed and the branch is deleted.
• The feature’s UI/UX has been reviewed to ensure consistency and alignment with design guidelines.