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/trpc/routers/project.ts

@@ -5,7 +5,7 @@
 import { TRPCError } from '@trpc/server';
 import { z } from 'zod';
 import { join } from 'node:path';
-import { rm } from 'node:fs/promises';
+import { rm, access } from 'node:fs/promises';
 import type { ProcedureBuilder } from '../trpc.js';
 import { requireProjectRepository, requireProjectSyncManager } from './_helpers.js';
 import { cloneProject } from '../../git/clone.js';
@@ -69,7 +69,17 @@ export function projectProcedures(publicProcedure: ProcedureBuilder) {
           }
         }
 
-        return project;
+        // Check for preview config
+        let hasPreviewConfig = false;
+        if (ctx.workspaceRoot) {
+          const clonePath = join(ctx.workspaceRoot, getProjectCloneDir(input.name, project.id));
+          try {
+            await access(join(clonePath, '.cw-preview.yml'));
+            hasPreviewConfig = true;
+          } catch { /* no config */ }
+        }
+
+        return { ...project, hasPreviewConfig };
       }),
 
     listProjects: publicProcedure