Create more end-to-end tests

### What feature do you want to see added?

Create more end-to-end tests to cover more screens and more of the user journey.

### Why do you want this feature? Does it solve a problem?

A small initial suite of end-to-end tests were created in #231 (for #27) using Playwright. This could be significantly expanded to cover more user journeys, giving greater confidence in the application and streamlining future improvements.

### How should the feature be implemented?

Create additional tests in the `/e2e` folder covering more screens.

Consider how the files should be named and structured.

Consider whether additional pre-existing database content is needed, and if this can be generated dynamically (instead of adding to mockTestData).

### Additional context (if applicable)

Tests can be created gradually in multiple PRs by multiple people.

Start by reviewing the Playwright tests added in #231 and the existing files in /e2e, then identify an uncovered screen or user journey. Check mockTestData and the current database setup to decide whether fixtures are needed. Done means an additional end-to-end journey is covered by a clearly named, passing test.

Written by the indexing model from the issue text.