test(browser): repair isolated full-stack acceptance journeys

[akemmanuel]

Summary

Repair the existing browser acceptance journeys so they can support issue verification against fresh, isolated test Hosts.

• Isolate HOME/configuration as well as Host data and project fixtures; do not import the operator's personal settings or skills.
• Wait for the public identity policy before opening the app, and allow a bounded cold frontend startup.
• Use current public controls: New Chat, profile-menu sign out, Models, People, and System.
• Reopen the persisted Session after reload before asserting durable transcript contents, including translated/responsive checks.
• Keep bounded fake-provider diagnostics for failures.

Verification

Both real agent-browser journeys pass after formatting/checks:

• node --experimental-strip-types scripts/browser-acceptance.ts: PASS.
• node --experimental-strip-types scripts/browser-acceptance-multi-user.ts: PASS.
• pnpm run check, pnpm run slop-check, git diff --check: PASS.

The journeys cover fixture read tools, queue/edit/reorder/send-now/abort, saved transcript reopening, settings, mocked skill controls, responsive/accessibility/language invariants, and multi-user identity/grants/models/sharing/public-link boundaries. No real providers, mail, production data, or Docker mutations are involved.

Automatic selected-chat restoration is not asserted: transcript persistence is checked by explicitly reopening the saved Session. Existing Better Auth startup schema diagnostics were not suppressed. These fixture journeys are not deployed acceptance for the issue fixes.