Add e2e coverage for the top-bar project switcher

Covers the switcher's visibility and dropdown contents, that switching projects scopes the page's data to the newly active project, and that the selection persists across navigation.

File: `e2e/project/project-switcher.spec.ts`. Verified: 8 passed (6 tests + 2 cleanup).

JIRA Issue: FR-3296

Start with e2e/project/project-switcher.spec.ts and review the existing project-switcher coverage. Run the spec and confirm coverage for switcher visibility, dropdown contents, project-scoped page data, and persistence across navigation; done means these scenarios pass along with the cleanup checks.

Written by the indexing model from the issue text.