igrantio-backend-sselisted

# iGrant.io backend SSE ## When to use To notify the browser the moment an OWS webhook lands, instead of polling the OWS history endpoint. Pairs with `igrantio-backend-webhooks` (which fills the store) and `igrantio-frontend-client`'s SSE consumer. Composed by the issuer/verifier backends. ## Prerequisites - An **iGrant.io Organisation Wallet Suite (OWS) API key**. Get it from [support@igrant.io](mailto:support@igrant.io). Keep it on the server, in an environment variable or a secret manager. The browser never sees it. - The **OWS environment** the key belongs to. The default is **demo** (`https://demo-api.igrant.io`). Use **staging** (`https://staging-api.igrant.io`) only when the integrator asks for it. A key works only in its own environment. ## Ask the integrator first Ask one question at a time. Wait for the answer. Give the recommended default with each question. Look up facts in the project (framework, environment variables, an existing backend) instead of asking for them. Record the answers before you write code. 1. **Environment** - demo or staging? _Default demo (`https://demo-api.igrant.io`); a switch later is a configuration change._ 2. **API key** - do you have the OWS API key for that environment? If not, request it from [support@igrant.io](mailto:support@igrant.io) before you continue. 3. **Event store** - in-memory or shared? _Shared for more than one instance._ 4. **Frontend origin** - which origins may open the stream (CORS)? ## Wh