P6: convert reactor to platform infrastructure

Refactor of reactor to use BaseNodeAdapter + commandRegistry + statusBadge.
reactor follows the platform refactor plan in .claude/refactor/MODULE_SPLIT.md.
Tests stay green; CONTRACT.md generated; legacy aliases preserved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/edge/missing-child.edge.test.js

@@ -2,24 +2,25 @@ const test = require('node:test');
 const assert = require('node:assert/strict');
 
 const NodeClass = require('../../src/nodeClass');
+const commands = require('../../src/commands');
+const { createRegistry } = require('generalFunctions');
 const { makeNodeStub, makeREDStub } = require('../helpers/factories');
 
-test('registerChild with unknown node id is ignored without throwing', () => {
+test('registerChild with unknown node id is ignored without throwing', async () => {
   const inst = Object.create(NodeClass.prototype);
   const node = makeNodeStub();
 
   inst.node = node;
   inst.RED = makeREDStub();
   inst.source = {
-    childRegistrationUtils: {
-      registerChild() {},
-    },
+    logger: { warn: () => {}, info: () => {}, debug: () => {}, error: () => {} },
+    childRegistrationUtils: { registerChild() {} },
   };
-
+  inst._commands = createRegistry(commands, { logger: inst.source.logger });
   inst._attachInputHandler();
 
-  assert.doesNotThrow(() => {
-    node._handlers.input(
+  await assert.doesNotReject(async () => {
+    await node._handlers.input(
       { topic: 'registerChild', payload: 'missing-child', positionVsParent: 'upstream' },
       () => {},
       () => {},