feat(events): add competitor number (bib) support

Allow participants to set their bib/competitor number per event.
Display as badge next to username in participant lists.

- Add competitorNumber field to EventParticipant model
- Add PUT /events/:slug/competitor-number endpoint
- Include competitorNumber in heats/me and heats/all responses
- Add input field in HeatsBanner component
- Display badge in UserListItem component
- Add unit tests for competitor number feature

backend/src/routes/events.js

@@ -643,6 +643,14 @@ router.get('/:slug/heats/me', authenticate, async (req, res, next) => {
       });
     }
 
+    // Get user's participation (for competitor number)
+    const participation = await prisma.eventParticipant.findUnique({
+      where: {
+        userId_eventId: { userId, eventId: event.id },
+      },
+      select: { competitorNumber: true },
+    });
+
     // Get user's heats
     const heats = await prisma.eventUserHeat.findMany({
       where: {
@@ -675,6 +683,7 @@ router.get('/:slug/heats/me', authenticate, async (req, res, next) => {
     res.json({
       success: true,
       count: heats.length,
+      competitorNumber: participation?.competitorNumber || null,
       data: heats,
     });
   } catch (error) {
@@ -700,6 +709,18 @@ router.get('/:slug/heats/all', authenticate, async (req, res, next) => {
       });
     }
 
+    // Get all participants with competitor numbers
+    const participants = await prisma.eventParticipant.findMany({
+      where: { eventId: event.id },
+      select: {
+        userId: true,
+        competitorNumber: true,
+      },
+    });
+    const competitorNumbers = new Map(
+      participants.map((p) => [p.userId, p.competitorNumber])
+    );
+
     // Get all heats with user info
     const heats = await prisma.eventUserHeat.findMany({
       where: {
@@ -741,6 +762,7 @@ router.get('/:slug/heats/all', authenticate, async (req, res, next) => {
           userId: heat.user.id,
           username: heat.user.username,
           avatar: heat.user.avatar,
+          competitorNumber: competitorNumbers.get(userId) || null,
           heats: [],
         });
       }
@@ -768,6 +790,70 @@ router.get('/:slug/heats/all', authenticate, async (req, res, next) => {
   }
 });
 
+// PUT /api/events/:slug/competitor-number - Set competitor number (bib number)
+router.put('/:slug/competitor-number', authenticate, async (req, res, next) => {
+  try {
+    const { slug } = req.params;
+    const { competitorNumber } = req.body;
+    const userId = req.user.id;
+
+    // Validate competitor number (positive integer or null)
+    if (competitorNumber !== null && competitorNumber !== undefined) {
+      const num = parseInt(competitorNumber, 10);
+      if (isNaN(num) || num < 1 || num > 9999) {
+        return res.status(400).json({
+          success: false,
+          error: 'Competitor number must be between 1 and 9999',
+        });
+      }
+    }
+
+    // Find event
+    const event = await prisma.event.findUnique({
+      where: { slug },
+      select: { id: true },
+    });
+
+    if (!event) {
+      return res.status(404).json({
+        success: false,
+        error: 'Event not found',
+      });
+    }
+
+    // Check if user is participant
+    const participant = await prisma.eventParticipant.findUnique({
+      where: {
+        userId_eventId: { userId, eventId: event.id },
+      },
+    });
+
+    if (!participant) {
+      return res.status(403).json({
+        success: false,
+        error: 'You must be a participant to set competitor number',
+      });
+    }
+
+    // Update competitor number
+    const updated = await prisma.eventParticipant.update({
+      where: {
+        userId_eventId: { userId, eventId: event.id },
+      },
+      data: {
+        competitorNumber: competitorNumber ? parseInt(competitorNumber, 10) : null,
+      },
+    });
+
+    res.json({
+      success: true,
+      competitorNumber: updated.competitorNumber,
+    });
+  } catch (error) {
+    next(error);
+  }
+});
+
 // DELETE /api/events/:slug/heats/:id - Delete specific heat
 router.delete('/:slug/heats/:id', authenticate, async (req, res, next) => {
   try {