Add WEBSOCKET_ONLY_MODE to disable REST routes in websocket deployment

[Copilot]

Websocket deployment (api-ws pods) was loading and exposing all REST API routes despite only serving GraphQL subscriptions, unnecessarily consuming memory and increasing attack surface.

Changes

• src/types.ts: Added WEBSOCKET_ONLY_MODE environment variable
• src/index.ts: Wrapped REST route registrations in conditional check
  • Routes skipped when WEBSOCKET_ONLY_MODE=true: /v1/*, /icon, /lettericons, /freyja, /rss/*, /alerts/*, /notifications/*, /webhooks/*, /integrations/*, all other REST routes
  • Always available: /health, /liveness, /graphql with subscriptions
• .infra/index.ts: Set WEBSOCKET_ONLY_MODE=true for websocket deployment

Example

const isWebsocketOnly = process.env.WEBSOCKET_ONLY_MODE === 'true';

// Skip all REST routes when in websocket-only mode
if (!isWebsocketOnly) {
  app.register(compatibility, { prefix: '/v1' });
  app.register(proxy, { prefix: '/icon' });
  app.register(routes, { prefix: '/' });
}

Other deployments (api, api-bg, api-temporal, api-private) are unaffected.

Original prompt

When running the websocket deployment, I do not want to also expose regular API since it will just consume resources being available

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