Uninstall E2E apps via the Admin API instead of the store admin UI

[isaacroldan]

WHY are these changes introduced?

E2E teardown uninstalls apps by clicking through the store admin UI in Playwright — Polaris selectors, an uninstall-reason survey modal, and hard-coded waits. It is the flakiest step of teardown, and because store deletion and app deletion are both gated on a successful uninstall, one flaky modal interaction leaks a store and an app. Leaked apps are what drive the test org toward the 5,000-app cap.

WHAT is this pull request doing?

Replaces the browser-driven uninstall with two HTTP requests in a new setup/admin-api.ts:

1. Mint an app access token with the client credentials grant (POST /admin/oauth/access_token). The grant applies because the E2E org owns both the app and the dev store. The client secret comes from app env show.
2. Call the appUninstall Admin API mutation, which uninstalls the calling app. No scopes required.

Details:

• The token mint can transiently return application_cannot_be_found right after app creation while records propagate, so it retries briefly (3 attempts, 5s apart). Verified empirically: bad client_id → application_cannot_be_found, bad secret → invalid_request, not installed → app_not_installed.
• No browser fallback. The API path is deterministic; a failure should fail the test loudly instead of hiding behind the flaky click-through. The per-run cleanup jobs remain the safety net.
• Harness-side API requests now send the loadtest header (loadtestHeaderRecord()), matching what the Playwright browser context already does.
• Store-flow specs pass appDir to teardownAll and remove the temp app dir after teardown, since the API path reads the app config from disk.

Validated locally end to end: teardown logs show app uninstalled via admin API followed by CLI-confirmed store deletion in repeated runs of toml-config.spec.ts.

Follow-up (separate PR): app deletion still drives the Dev Dashboard UI and remains the top flake/leak source (scrollIntoViewIfNeeded: Timeout 5000ms).

How to test your changes?

Run any store-flow spec with teardown logging, e.g.:

cd packages/e2e
DEBUG=1 pnpm exec playwright test tests/toml-config.spec.ts -g "dev starts with fully populated toml" --workers=1

The teardown section should log uninstalling app via admin API → app uninstalled via admin API → store deletion confirmed by CLI.

Measuring impact

• n/a — internal test harness change, no user-facing impact

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