feat: add rule dispatch, cross-plugin API, and Docker integration test

Wire rule registry and authenticated callbacks into both client and server
runtimes; expose __yonexusClient / __yonexusServer on globalThis for
cross-plugin communication. Add Docker-based integration test with
server-test-plugin (test_ping echo) and client-test-plugin (test_pong
receiver), plus docker-compose setup. Fix transport race condition where
a stale _connections entry caused promoteToAuthenticated to silently fail.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/docker/client-test-plugin/openclaw.plugin.json

@@ -0,0 +1,13 @@
+{
+  "id": "yonexus-client-test",
+  "name": "Yonexus Client Test Plugin",
+  "version": "0.1.0",
+  "description": "Test plugin for Yonexus.Client rule routing",
+  "entry": "./index.mjs",
+  "permissions": [],
+  "configSchema": {
+    "type": "object",
+    "additionalProperties": false,
+    "properties": {}
+  }
+}