fix: support partial updates in tournament PUT endpoint

- Change PUT endpoint to only include fields present in the request
- Add support for team configuration fields (teamDurability, partnerRotation, allowByes)
- Fix contradictory test that expected resetting allowTies when not provided
- When a field is not in the request, it is preserved (not modified)

Fixes issue where Save Configuration button would fail with
'Tournament name is required' error.

src/app/api/tournaments/[id]/route.ts

@@ -151,28 +151,36 @@ export async function PUT(request: Request, { params }: RouteParams) {
       ownerId,
       targetScore,
       allowTies,
+      teamDurability,
+      partnerRotation,
+      allowByes,
     } = body;
 
-    // Validate required fields
-    if (!name || typeof name !== 'string' || name.trim().length === 0) {
-      return NextResponse.json(
-        { error: "Tournament name is required" },
-        { status: 400 }
-      );
+    // Validate name only if it's being updated
+    if (body.hasOwnProperty('name')) {
+      if (!name || typeof name !== 'string' || name.trim().length === 0) {
+        return NextResponse.json(
+          { error: "Tournament name is required" },
+          { status: 400 }
+        );
+      }
     }
 
-    // Prepare update data
-    const updateData: Record<string, unknown> = {
-      name: name.trim(),
-      description: description || null,
-      eventDate: eventDate ? new Date(eventDate) : null,
-      eventType: eventType || "tournament",
-      tournamentType: tournamentType || "individual",
-      format: format || "round_robin",
-      maxParticipants: maxParticipants ? parseInt(maxParticipants) : null,
-      targetScore: targetScore ? parseInt(targetScore) : null,
-      allowTies: allowTies ?? false,
-    };
+    // Prepare update data - only include fields that are present in the request
+    const updateData: Record<string, unknown> = {};
+
+    if (body.hasOwnProperty('name')) updateData.name = name.trim();
+    if (body.hasOwnProperty('description')) updateData.description = description || null;
+    if (body.hasOwnProperty('eventDate')) updateData.eventDate = eventDate ? new Date(eventDate) : null;
+    if (body.hasOwnProperty('eventType')) updateData.eventType = eventType || "tournament";
+    if (body.hasOwnProperty('tournamentType')) updateData.tournamentType = tournamentType || "individual";
+    if (body.hasOwnProperty('format')) updateData.format = format || "round_robin";
+    if (body.hasOwnProperty('maxParticipants')) updateData.maxParticipants = maxParticipants ? parseInt(maxParticipants) : null;
+    if (body.hasOwnProperty('targetScore')) updateData.targetScore = targetScore ? parseInt(targetScore) : null;
+    if (body.hasOwnProperty('allowTies')) updateData.allowTies = allowTies ?? false;
+    if (body.hasOwnProperty('teamDurability')) updateData.teamDurability = teamDurability || "permanent";
+    if (body.hasOwnProperty('partnerRotation')) updateData.partnerRotation = partnerRotation || "none";
+    if (body.hasOwnProperty('allowByes')) updateData.allowByes = allowByes ?? true;
 
     // Only allow status updates if they don't conflict with auto-calculation
     if (status) {