Yjs Electric provider example (#1508)

A codemirror example with Yjs using Electric for sync

Contains an Y-Electric connection provider that we will extract and ship as a separate package.

examples/nextjs-example/app/shape-proxy/route.ts

@@ -41,4 +41,4 @@ export async function GET(request: Request) {
     })
   }
   return resp
-}
+}