feat: Add agent preview integration with auto-teardown and simplified commands

- Add agentId label to preview containers (cw.agent-id) for tracking
- Add startForAgent/stopByAgentId methods to PreviewManager
- Auto-teardown: previews torn down on agent:stopped event
- Conditional preview prompt injection for execute/refine/discuss agents
- Agent-simplified CLI: cw preview start/stop --agent <id>
- cw preview setup command with --auto mode for guided config generation
- hasPreviewConfig hint on cw project register output
- New tRPC procedures: startPreviewForAgent, stopPreviewByAgent

apps/server/preview/compose-generator.ts

@@ -128,6 +128,7 @@ export function generateLabels(opts: {
   gatewayPort: number;
   previewId: string;
   mode: 'preview' | 'dev';
+  agentId?: string;
 }): Record<string, string> {
   const labels: Record<string, string> = {
     [PREVIEW_LABELS.preview]: 'true',
@@ -143,5 +144,9 @@ export function generateLabels(opts: {
     labels[PREVIEW_LABELS.phaseId] = opts.phaseId;
   }
 
+  if (opts.agentId) {
+    labels[PREVIEW_LABELS.agentId] = opts.agentId;
+  }
+
   return labels;
 }