Add UK chat route

[SakshiKekre]

Summary

• Add Vercel rewrites for /uk/chat and /uk/chat/:path* to mount the policyengine-uk-chat app as a full-page multizone route
• Keep the integration minimal so local demos can use the uk-chat app now, then production can use the merged uk-chat deployment later

Verification

• node -e "JSON.parse(require('fs').readFileSync('vercel.json','utf8')); console.log('vercel.json ok')"
• cd app && bun run vitest src/tests/unit/config/vercel.test.ts

Notes

• This route depends on Abstract chat simulation backends policyengine-uk-chat#41 for the model backend selector and Python backend support.
• Until that PR is merged/deployed, demos should use a fully local uk-chat setup or a manually configured branch backend.

[vercel]

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

Project	Deployment	Actions	Updated (UTC)
policyengine-app-v2	Ready	Preview, Comment	Apr 29, 2026 6:26pm
policyengine-calculator	Ready	Preview, Comment	Apr 29, 2026 6:26pm
policyengine-calculator-next	Ready	Preview, Comment	Apr 29, 2026 6:26pm
policyengine-website	Ready	Preview, Comment	Apr 29, 2026 6:26pm