refactor(providers-branch): split opencode test into its own file

Moves the opencode test case out of factory.test.ts into
opencode.factory.test.ts so the /add-opencode skill can install the
opencode bundle as a pure file copy — no in-place merging of the shared
factory.test.ts required. Keeps factory.test.ts identical to v2 trunk.

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

container/agent-runner/src/providers/factory.test.ts

@@ -3,17 +3,12 @@ import { describe, it, expect } from 'bun:test';
 import { createProvider, type ProviderName } from './factory.js';
 import { ClaudeProvider } from './claude.js';
 import { MockProvider } from './mock.js';
-import { OpenCodeProvider } from './opencode.js';
 
 describe('createProvider', () => {
   it('returns ClaudeProvider for claude', () => {
     expect(createProvider('claude')).toBeInstanceOf(ClaudeProvider);
   });
 
-  it('returns OpenCodeProvider for opencode', () => {
-    expect(createProvider('opencode')).toBeInstanceOf(OpenCodeProvider);
-  });
-
   it('returns MockProvider for mock', () => {
     expect(createProvider('mock')).toBeInstanceOf(MockProvider);
   });

container/agent-runner/src/providers/opencode.factory.test.ts

@@ -0,0 +1,10 @@
+import { describe, it, expect } from 'bun:test';
+
+import { createProvider } from './factory.js';
+import { OpenCodeProvider } from './opencode.js';
+
+describe('createProvider (opencode)', () => {
+  it('returns OpenCodeProvider for opencode', () => {
+    expect(createProvider('opencode')).toBeInstanceOf(OpenCodeProvider);
+  });
+});