feat: tmpo undo to revert a previous action

[DylanDevelops]

Pull Request Checklist

• I have read and followed the contribution guidelines.
• My pull request targets the main branch of tmpo.
• I have tested these changes locally on my machine.

Closes #116

Description

This pull request introduces an "undo" feature to the application, allowing users to revert their most recent time-tracking action. The implementation tracks user actions (such as start, stop, pause, resume, manual entry creation, and deletion) and provides a new undo command to roll back the last action. The change also includes comprehensive tests for the new undo functionality and its integration with the storage layer.

Undo Feature Implementation

• Added a new undo command (UndoCmd) that allows users to undo their most recent time-tracking action. The command provides user feedback, confirmation prompts, and handles various action types appropriately.
• Integrated action tracking into all major time entry commands (start, stop, pause, resume, manual, delete) by saving an UndoAction to the database after each action. [1] [2] [3] [4] [5] [6]
• Registered the new undo command in the application's root command.

Storage Layer Enhancements

• Added a new UndoAction type and related methods to the storage layer for saving, retrieving, and clearing the last action. Also added methods to "uncomplete" (re-open) an entry and restore deleted entries, supporting the undo logic.

Testing

• Added comprehensive tests for both the undo command logic and the storage layer's undo functionality, including edge cases and error handling. [1] [2]

User Interface

• Added a new emoji constant (EmojiUndo) to visually indicate undo actions in the UI.