feat: add GIF Mood Board workshop

- New workshop where each team member shares up to 5 GIFs with notes to express their weekly mood
- Per-user week rating (1-5 stars) visible next to each member's section
- Masonry-style grid with adjustable column count (3/4/5) toggle
- Handwriting font (Caveat) for GIF notes
- Full real-time collaboration via SSE
- Clean migration (add_gif_mood_workshop) safe for production deploy
- DB backup via cp before each migration in docker-entrypoint

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/api/gif-mood/[id]/subscribe/route.ts

@@ -0,0 +1,112 @@
+import { auth } from '@/lib/auth';
+import { canAccessGifMoodSession, getGifMoodSessionEvents } from '@/services/gif-mood';
+
+export const dynamic = 'force-dynamic';
+
+// Store active connections per session
+const connections = new Map<string, Set<ReadableStreamDefaultController>>();
+
+export async function GET(request: Request, { params }: { params: Promise<{ id: string }> }) {
+  const { id: sessionId } = await params;
+  const session = await auth();
+
+  if (!session?.user?.id) {
+    return new Response('Unauthorized', { status: 401 });
+  }
+
+  const hasAccess = await canAccessGifMoodSession(sessionId, session.user.id);
+  if (!hasAccess) {
+    return new Response('Forbidden', { status: 403 });
+  }
+
+  const userId = session.user.id;
+  let lastEventTime = new Date();
+  let controller: ReadableStreamDefaultController;
+
+  const stream = new ReadableStream({
+    start(ctrl) {
+      controller = ctrl;
+
+      if (!connections.has(sessionId)) {
+        connections.set(sessionId, new Set());
+      }
+      connections.get(sessionId)!.add(controller);
+
+      const encoder = new TextEncoder();
+      controller.enqueue(
+        encoder.encode(`data: ${JSON.stringify({ type: 'connected', userId })}\n\n`)
+      );
+    },
+    cancel() {
+      connections.get(sessionId)?.delete(controller);
+      if (connections.get(sessionId)?.size === 0) {
+        connections.delete(sessionId);
+      }
+    },
+  });
+
+  const pollInterval = setInterval(async () => {
+    try {
+      const events = await getGifMoodSessionEvents(sessionId, lastEventTime);
+      if (events.length > 0) {
+        const encoder = new TextEncoder();
+        for (const event of events) {
+          if (event.userId !== userId) {
+            controller.enqueue(
+              encoder.encode(
+                `data: ${JSON.stringify({
+                  type: event.type,
+                  payload: JSON.parse(event.payload),
+                  userId: event.userId,
+                  user: event.user,
+                  timestamp: event.createdAt,
+                })}\n\n`
+              )
+            );
+          }
+          lastEventTime = event.createdAt;
+        }
+      }
+    } catch {
+      clearInterval(pollInterval);
+    }
+  }, 2000);
+
+  request.signal.addEventListener('abort', () => {
+    clearInterval(pollInterval);
+  });
+
+  return new Response(stream, {
+    headers: {
+      'Content-Type': 'text/event-stream',
+      'Cache-Control': 'no-cache',
+      Connection: 'keep-alive',
+    },
+  });
+}
+
+export function broadcastToGifMoodSession(sessionId: string, event: object) {
+  try {
+    const sessionConnections = connections.get(sessionId);
+    if (!sessionConnections || sessionConnections.size === 0) {
+      return;
+    }
+
+    const encoder = new TextEncoder();
+    const message = encoder.encode(`data: ${JSON.stringify(event)}\n\n`);
+
+    for (const controller of sessionConnections) {
+      try {
+        controller.enqueue(message);
+      } catch {
+        sessionConnections.delete(controller);
+      }
+    }
+
+    if (sessionConnections.size === 0) {
+      connections.delete(sessionId);
+    }
+  } catch (error) {
+    console.error('[SSE Broadcast] Error broadcasting:', error);
+  }
+}