refactor: rename openclaw -> clawhubadapter, add ClawHub search/install, fix agent interrupt

- Rename internal/plugins/openclaw/ -> internal/plugins/clawhubadapter/
- Add RegistryDispatcher with 5 sub-registries (Tool, Provider, Channel, Stage, Cap)
- Add clawhubadapter_search tool for ClawHub marketplace search
- Add clawhub: prefix support for installing from ClawHub (ZIP/tgz auto-detect)
- Add CallProvider RPC and provider/call routing
- Fix QQ interrupt: check interceptCh before/after each tool execution

internal/plugins/clawhubadapter/testdata/oc-pkg/lib/entry.js

@@ -0,0 +1,33 @@
+module.exports = {
+  default: {
+    id: 'oc-pkg',
+    name: 'OC Package',
+    version: '2.0.0',
+    description: 'Test plugin discovered via package.json extensions',
+    register(api) {
+      api.registerTool({
+        name: 'add',
+        description: 'Add two numbers',
+        parameters: {
+          type: 'object',
+          properties: {
+            a: { type: 'number', description: 'First number' },
+            b: { type: 'number', description: 'Second number' },
+          },
+          required: ['a', 'b'],
+        },
+        execute(id, params) {
+          return String(params.a + params.b);
+        },
+      });
+
+      api.registerTool({
+        name: 'info',
+        description: 'Return plugin info',
+        execute(id, params) {
+          return JSON.stringify({ id: this.id, name: this.name, version: this.version });
+        },
+      });
+    },
+  },
+};