refactor: extract dashboard and message-runtime from index.ts

- Extract dashboard code into src/dashboard.ts
- Extract message runtime into src/message-runtime.ts
- Improve group-queue with better concurrency handling
- Update agent-runner with enhanced env/config passing
- Simplify DB operations and cleanup unused code
- Update README for Codex SDK architecture

setup/container.ts

@@ -29,14 +29,14 @@ export async function run(_args: string[]): Promise<void> {
   // Verify runner entry points exist
   const agentRunner = path.join(
     projectRoot,
-    'container',
+    'runners',
     'agent-runner',
     'dist',
     'index.js',
   );
   const codexRunner = path.join(
     projectRoot,
-    'container',
+    'runners',
     'codex-runner',
     'dist',
     'index.js',