refactor(worker): extract AgentRuntime interface, shared provider helpers, and adapter registry

apps/agent-worker/tests/unit/maintenance-workspace-cleanup.test.ts

@@ -156,6 +156,7 @@ describe('maintenance workspace cleanup', () => {
         boxHandle: { boxName: 'spoon-box-tester', release },
         githubToken: 'github-token',
         redact: (value: string) => value,
+        runtime: 'codex',
         containerName: 'spoon-agent-job-maintenance',
         opencodeSession: {
           client: {} as never,