Vercel deployment has no backend route for /api requests

[priscaenoch]

Problem

vercel.json rewrites everything except /api/ to index.html:

{ "source": "/((?!api/).*)", "destination": "/index.html" }

The exclusion correctly avoids rewriting API calls, but nothing else in the configuration serves or proxies /api/. On Vercel those requests hit the static deployment and 404, so the app has no backend.

By contrast, the Docker deployment does define a proxy in nginx.conf (location /api/ { proxy_pass http://indexer:3001; }). The two deployment targets are therefore inconsistent: Docker proxies the API, Vercel does not.

What needs to be done

• Decide how the hosted deployment reaches the indexer. Options: a rewrites entry proxying /api/:path* to the public indexer URL, or configuring an absolute API base URL at build time (see issue Make the backend API base URL configurable for production builds #1) and dropping the /api path convention on Vercel.
• Implement the chosen approach in vercel.json (and align with the configurable API base work in issue Make the backend API base URL configurable for production builds #1).
• Document, in the README, how each deployment target (dev proxy, Docker/nginx, Vercel) reaches the backend.

Files

• vercel.json
• README.md
• coordinate with src/api.ts / API base configuration

Acceptance deliverables

• A Vercel deployment can reach a configured indexer; /api calls no longer 404.
• The three deployment paths are documented and consistent.

Tests to pass

• Documented verification that a deployed build performs a successful API request.