fix: use 'connect' method with auth.token for gateway handshake

Gateway uses JSON-RPC method 'connect' (not 'hello') with auth
object containing token field.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugin/index.ts

@@ -220,13 +220,14 @@ export default {
           };
 
           client.onopen = () => {
+            // Gateway uses "connect" method with auth in params
             client.send(JSON.stringify({
               jsonrpc: '2.0',
-              method: 'hello',
+              method: 'connect',
               params: {
                 clientName: 'harbor-forge-calendar',
                 mode: 'backend',
-                ...(gwToken ? { token: gwToken } : {}),
+                ...(gwToken ? { auth: { token: gwToken } } : {}),
               },
               id: 1,
             }));