fix: restore brainstorming feature with missing socket server and real-time events

memento-note/app/api/brainstorm/[sessionId]/dismiss/route.ts

@@ -3,6 +3,7 @@ import prisma from '@/lib/prisma'
 import { auth } from '@/auth'
 import { z } from 'zod'
 import { verifyParticipant, logActivity, captureSnapshot } from '@/lib/brainstorm-collab'
+import { emitToSession } from '@/lib/socket-emit'
 
 const dismissSchema = z.object({
   ideaId: z.string().min(1),
@@ -56,6 +57,14 @@ export async function POST(
 
     await logActivity(sessionId, 'idea_dismissed', session.user.id, { ideaTitle: idea.title })
 
+    await emitToSession(sessionId, 'idea:dismissed', { ideaId, userId: session.user.id })
+    await emitToSession(sessionId, 'activity:new', {
+      action: 'idea_dismissed',
+      userId: session.user.id,
+      userName: session.user.name || 'Guest',
+      details: { ideaTitle: idea.title, ideaId }
+    })
+
     await captureSnapshot(sessionId, `Dismissed: ${idea.title}`).catch(() => {})
 
     return NextResponse.json({ success: true })