[neuroscr]

The Checks workflow now validates the full server/Next production build and confidential runtime suite, plus a separate Chromium browser job with a 60-minute limit. The standalone build disables confidential mode because it has no deployment release manifest; the browser harness builds confidential mode with synthetic release and identity fixtures.

Fix two existing browser-test issues exposed by the new gate: align the synthetic admin provider email with the allowed fixture domain, and wait for loader removal after delayed hydration instead of a nonexistent data-loaded attribute.

Validation:

• Production build, typecheck, and all 117 runtime tests passed locally.
• GitHub check passed on a410650, including unit/service tests and the new build/runtime steps.
• That browser run passed 52 tests and failed only the stale homepage-loader assertion; four dependent tests did not run.
• Both homepage-loader tests now pass locally after the assertion fix. Full latest-commit CI is pending.
• The earlier Jest worker-exit warning is not confirmed fixed; local open-handle diagnostics did not reproduce it.

Keep in draft until the full browser job passes.