docs: point readers at @opensea/sdk/stream (#528)

The Stream client now ships inside @opensea/sdk at the @opensea/sdk/stream
subpath, and @opensea/stream-js is deprecated at 0.4.0. Anyone landing here
should be sent to the maintained code rather than following install
instructions for a package that will not be updated again.

Adds a notice at the top with the uninstall/install commands, the two-line
import diff, and the breaking changes, each linked to the migration guide.

Also repoints the Documentation link from /reference/stream-js to
/reference/stream-api. The old slug redirects, but this is the last thing a
reader here will see, so it may as well be the live URL.

Left as is: the rest of the README still describes the 0.4.0 API, which is what
the last published version actually does. Rewriting it would misrepresent the
package that is still on npm.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: ryanio

README.md

@@ -1,3 +1,32 @@
+> [!IMPORTANT]
+> ## This package has moved to `@opensea/sdk`
+>
+> `@opensea/stream-js` is deprecated and no longer maintained. Its last published version is `0.4.0`. The Stream client now ships inside the OpenSea SDK at the `@opensea/sdk/stream` subpath, where it is actively maintained.
+>
+> ```bash
+> npm uninstall @opensea/stream-js ws node-localstorage
+> npm install @opensea/sdk
+> ```
+>
+> ```diff
+> -import { OpenSeaStreamClient } from "@opensea/stream-js";
+> +import { OpenSeaStreamClient } from "@opensea/sdk/stream";
+>
+> -const client = new OpenSeaStreamClient({ token: "YOUR_API_KEY" });
+> +const client = new OpenSeaStreamClient({ apiKey: "YOUR_API_KEY" });
+> ```
+>
+> Every event type, payload, and `on*` method is unchanged. There are a few small breaking changes, all covered in the [migration guide](https://github.com/ProjectOpenSea/opensea-sdk/blob/main/developerDocs/stream-migration.md):
+>
+> - Node no longer needs `ws` or `node-localstorage`. Node 22+ and browsers supply a global `WebSocket`, and `sessionStorage` was only read by an unused long-poll fallback.
+> - `apiKey` replaces `token`, which still works but is deprecated.
+> - Unsubscribing removes one handler instead of leaving the whole collection channel.
+> - Node 22 is the minimum, since Node 20 reached end of life in April 2026.
+>
+> The client no longer depends on `phoenix`, so importing `@opensea/sdk/stream` pulls in no third-party runtime code.
+>
+> Repository: [ProjectOpenSea/opensea-sdk](https://github.com/ProjectOpenSea/opensea-sdk)  |  Documentation: [docs.opensea.io/reference/stream-api](https://docs.opensea.io/reference/stream-api)
+
 <p align="center">
   <img src="./img/banner.png" />
 </p>
@@ -23,7 +52,7 @@ A TypeScript SDK for receiving updates from the OpenSea Stream API - pushed over
 
 This is a best effort delivery messaging system. Messages that are not received due to connection errors will not be re-sent. Messages may be delivered out of order. This SDK is offered as a beta experience as we work with developers in the ecosystem to make this a more robust and reliable system.
 
-Documentation: https://docs.opensea.io/reference/stream-js
+Documentation: https://docs.opensea.io/reference/stream-api
 
 # Installation