The `/setup` route no longer accepts `?role=analyst|admin`. The route
signature drops the `Literal[...] = Query(...)` parameter and the
silent admin-downgrade block (`if role == "admin" and not is_admin:
role = "analyst"`). The `role` ctx variable threaded into install.html
also goes away — Task 6 cleans up the template's role-tile UI and the
JS PAT-mint ternary.
`?role=` is silently ignored by FastAPI for unknown query params, so
existing bookmarks (none in production — the param was added in this
PR and never shipped) just degrade to the unified layout. No
RedirectResponse shim needed.
Tests: drop the entire `tests/test_setup_page_roles.py` file (eight
role-branching tests that no longer apply) and add
`tests/test_setup_page_unified.py` with three tests:
- `test_setup_page_renders_unified_layout`
- `test_setup_page_ignores_role_query_param`
- `test_setup_page_renders_marketplace_for_user_with_grants`
- `test_install_legacy_path_redirects_to_setup`
Also replace the role-aware `test_install_preview_*` tests in
test_web_ui.py with unified-layout assertions.
Plan: docs/superpowers/plans/2026-05-04-unified-setup-prompt.md task 5.
