Add console visual checks

docs/specs/testing-release-and-migration.md

@@ -7,7 +7,23 @@
 - contract tests from fixtures
 - migration tests for Alembic revisions and imports
 - consumer smokes for ops-hub and activity-core
-- optional Playwright visual checks once UI exists
+- Playwright visual checks for protected operator UI desktop and mobile layouts
+
+## Operator UI Visual Checks
+
+The protected `/console` route is checked with Playwright using `make visual-check`.
+The harness starts a disposable SQLite-backed Core Hub instance, seeds non-secret
+operator data, verifies unauthenticated access returns `401`, renders authenticated
+desktop and mobile screenshots, checks for horizontal overflow and overlapping
+major regions, and asserts full API key material is absent from DOM state and
+visual artifacts. Generated screenshots are written under `.local/visual-checks/`
+and must not be committed.
+
+Install the Chromium runtime once per workstation with:
+
+```bash
+make playwright-install
+```
 
 ## Release Gates