Add new base plugins (#13)

* chore: update CONTRIBUTING.md for improved validation steps and clarify registry.json handling

- Replace build step with validation command in contribution guidelines
- Emphasize not committing registry.json and clarify its regeneration by CI
- Enhance pre-commit script to handle timestamp-only changes for registry.json
- Update documentation to reflect new validation processes and plugin submission steps

* feat: add new Pomodoro plugin to TimeTracker

- Introduce a new Pomodoro plugin with version 1.0.0
- Include metadata such as author, repository link, description, and version compatibility
- Categorize the plugin under productivity with appropriate tags

* feat: add pomodoro timer plugin to TimeTracker

- Introduce a new Pomodoro Timer plugin with version 1.0.0.
- Include essential metadata such as author, repository link, description, and version compatibility.
- Categorize the plugin under productivity with relevant tags.

Signed-off-by: bthos <bthos@example.com>

* Add new base plugins

Signed-off-by: bthos <bthos@example.com>

---------

Signed-off-by: bthos <bthos@example.com>
Co-authored-by: bthos <bthos@example.com>

Author: bthos