Restore committed visual baselines and enforce CI comparison

[bntvllnt]

The visual suite has 305 cases but only 34 tracked screenshots. Storybook CI currently uses --update-snapshots, silently accepting visual changes and missing baselines. This blocks reliable regression evidence for #506.

Acceptance:

• Pin a reproducible Linux Playwright environment.
• Commit reviewed baseline images generated from main.
• Stabilize locale, timezone, and reduced-motion settings.
• Compare in CI without snapshot updates.
• Demonstrate comparison passes and a deliberately altered baseline fails.
• Keep baseline repair separate from Native feature changes.

[github-actions]

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