feat(ai): wire the four v1 companion tools into a shared registry

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/ai/agent/tools/index.test.js

@@ -0,0 +1,13 @@
+import { describe, it, expect } from 'vitest';
+import { companionRegistry } from '../../../../lib/ai/agent/tools/index.js';
+
+describe('companion registry', () => {
+  it('registers exactly the four v1 tools', () => {
+    expect(companionRegistry.listTools().map(t => t.name).sort())
+      .toEqual(['context', 'propose_change', 'read', 'search']);
+  });
+  it('exposes them in Anthropic shape', () => {
+    const tools = companionRegistry.toAnthropicTools();
+    expect(tools.every(t => t.name && t.input_schema && !('handler' in t))).toBe(true);
+  });
+});