fix: show jury group selector at top of assignments tab when none assigned

Previously showed "Select a jury group below" but the selector was
buried at the bottom (or not rendered at all when no jury was assigned).
Now shows the actual dropdown + "New Jury" button right where the
empty state message was.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/(admin)/admin/rounds/[roundId]/page.tsx

@@ -1787,8 +1787,48 @@ export default function RoundDetailPage() {
             {/* 1. Jury Members & Progress (merged) */}
             {!round?.juryGroupId ? (
               <Card>
-                <CardContent className="py-8 text-center">
+                <CardHeader>
-                  <p className="text-sm text-muted-foreground">Select a jury group below to get started.</p>
+                  <div className="flex items-center justify-between">
+                    <div>
+                      <CardTitle className="text-base">Jury Group</CardTitle>
+                      <CardDescription>
+                        Select or create a jury group to get started
+                      </CardDescription>
+                    </div>
+                    <Button size="sm" variant="outline" onClick={() => setCreateJuryOpen(true)}>
+                      <Plus className="h-4 w-4 mr-1.5" />
+                      New Jury
+                    </Button>
+                  </div>
+                </CardHeader>
+                <CardContent>
+                  {juryGroups && juryGroups.length > 0 ? (
+                    <Select
+                      value="__none__"
+                      onValueChange={(value) => {
+                        if (value !== '__none__') {
+                          assignJuryMutation.mutate({ id: roundId, juryGroupId: value })
+                        }
+                      }}
+                      disabled={assignJuryMutation.isPending}
+                    >
+                      <SelectTrigger className="w-full sm:w-80">
+                        <SelectValue placeholder="Select jury group..." />
+                      </SelectTrigger>
+                      <SelectContent>
+                        <SelectItem value="__none__">No jury assigned</SelectItem>
+                        {juryGroups.map((jg: any) => (
+                          <SelectItem key={jg.id} value={jg.id}>
+                            {jg.name} ({jg._count?.members ?? 0} members)
+                          </SelectItem>
+                        ))}
+                      </SelectContent>
+                    </Select>
+                  ) : (
+                    <p className="text-sm text-muted-foreground">
+                      No jury groups exist yet. Create one to get started.
+                    </p>
+                  )}
                 </CardContent>
               </Card>
             ) : (