fix(web): Fix `index.html` caching issue in production

[koistya]

• Move GraphQL client extensions for Relay to api/schema.relay.graphql
• Add schemaExtensions setting to web/package.json/relay (config) + local schema extension example
• Fix the base API URL and index.html caching issue in the CFW script for production deployment
• Append x-continent, x-country, x-timezone headers to API requests during SSR (web/workers/proxy.ts)

web/package.json

{
  "...",
  "relay": {
    "src": ".",
    "schema": "../api/schema.graphql",
    "language": "typescript",
    "artifactDirectory": "./queries",
    "schemaExtensions": [
      "."
    ],
    "eagerEsModules": true
  }
}