Verify source map upload against a real Sentry org #24685

Emission is covered by tests, but nothing confirms sentry-cli accepts the artifact set we build. Upload from a real app to a real org and check a client stack trace symbolicates.

Needs SENTRY_ORG, SENTRY_PROJECT and SENTRY_AUTH_TOKEN. Wiring the mock Sentry server in dev-packages/test-utils would make this repeatable in CI afterwards.