Opt-out of Firebase tracking

An option should be provided in the settings (and eventually in one of the first-run screens) for users to be able to opt out of analytics tracking.

### Acceptance Criteria
1.
2.
3.

### Definition of Done
- [ ] Tested against acceptance criteria
- [ ] Tested against the assumptions of the user story
- [ ] The project builds without errors
- [ ] Unit tests are written and passing
- [ ] Tests on devices/browsers listed in the issue have passed
- [ ] QA performed & issues resolved
- [ ] Refactoring completed
- [ ] Any configuration or build changes documented
- [ ] Documentation updated
- [ ] Peer Code Review performed

Start by locating the Firebase analytics integration and the settings screen, then identify the first-run screen mentioned in the issue. Define the opt-out behavior for each entry point and verify it against the acceptance criteria, but those criteria are currently empty. Add unit tests and confirm the project builds and the relevant device or browser tests pass.

Written by the indexing model from the issue text.