refactor: route channel runtime via plugin api

src/docs/slash-commands-doc.test.ts

@@ -1,8 +1,18 @@
 import fs from "node:fs/promises";
 import path from "node:path";
-import { describe, expect, it } from "vitest";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
 
 import { listChatCommands } from "../auto-reply/commands-registry.js";
+import { setActivePluginRegistry } from "../plugins/runtime.js";
+import { createTestRegistry } from "../test-utils/channel-plugins.js";
+
+beforeEach(() => {
+  setActivePluginRegistry(createTestRegistry([]));
+});
+
+afterEach(() => {
+  setActivePluginRegistry(createTestRegistry([]));
+});
 
 function extractDocumentedSlashCommands(markdown: string): Set<string> {
   const documented = new Set<string>();