Add broken-site banner to Metaforecast

[michaelr524]

Summary

• Adds a yellow warning banner below the nav bar on all Metaforecast pages
• Banner text: "Notice: Metaforecast is currently experiencing issues and may not work as expected. We are working on fixing it."

Test plan

• Check Vercel preview deploy to confirm banner looks good
• Verify banner appears on all pages (home, about, status, etc.)

🤖 Generated with Claude Code

[changeset-bot]

⚠️ No Changeset found

Latest commit: 4c15fe1

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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💥 An error occurred when fetching the changed packages and changesets in this PR

Some errors occurred when validating the changesets config:
The package "@quri/evaluations" depends on the ignored package "@quri/squiggle-ai", but "@quri/evaluations" is not being ignored. Please add "@quri/evaluations" to the `ignore` option.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
metaforecast	Ready	Preview	Mar 16, 2026 0:03am
quri-hub	Ready	Preview	Mar 16, 2026 0:03am
squiggle-components	Ready	Preview	Mar 16, 2026 0:03am
squiggle-website	Ready	Preview	Mar 16, 2026 0:03am

2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
fermi-contest-2025-02	Ignored	Preview	Mar 16, 2026 0:03am
quri-ui	Ignored	Preview	Mar 16, 2026 0:03am