fix: flaky download file manifest e2e — wait for nav (#4828)

[frano-m]

Summary

Adds an explicit waitForURL between clickCard and the destination-page assertion in two Dataset e2e tests:

• displays download file manifest — the test cited in the CI failure. Click navigated to /datasets/{id}/export/download-manifest, but the assertion on .MuiButton-root:has-text("Request Link") polled an unmounted page and timed out with 18 × locator resolved to 0 elements.
• displays analyze in Terra — same shape (clickCard → destination-page UI assertion, no wait), so applied the same defence preemptively.

The other clickCard sites in the spec (displays download file manifest selected data, displays analyze in Terra selected data) are already navigation-aware via Promise.all([waitForRequest, clickCard]).

Inline regex was avoided — ROUTES.MANIFEST_DOWNLOAD and ROUTES.TERRA are already imported, so the wait uses a predicate (url.pathname.endsWith(ROUTES.X)) for clarity and DRY.

Closes #4828.

Test plan

• npx tsc --noEmit, npm run check-format pass
• npm run test:anvil-cmg — full anvil suite, 114/114 across chromium/firefox/webkit (2.6 min)
• Watch CI over the next several runs to confirm the Firefox flake is gone

Out of scope

A broader rewrite of anvil-dataset.spec.ts (test-id-based locators, role-based queries, dispatchEvent for click-swallowing, helper layout convention from anvil-filters.spec.ts) was considered and deferred — the spec is otherwise stable and the structure isn't itself flaky.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR addresses a flaky Playwright e2e in the AnVIL CMG dataset export flow by explicitly waiting for client-side navigation after clicking an export-method card, before asserting destination-page UI. This aligns the test behavior with the actual SPA routing timing (particularly on Firefox) and prevents assertions from polling a page that has already unmounted.

Changes:

• Add page.waitForURL(...) after clicking “Request File Manifest” to ensure the manifest download route is loaded before asserting the “Request Link” button.
• Add the same navigation wait after clicking “Analyze in Terra” before asserting that the Terra form is visible.

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