feat: add optional student nickname for informal display

Keep legal first and last names for formal lists; show DisplayFirstName on teams, calendars, and import matching so two Josiahs can be told apart.

Co-authored-by: Cursor <cursoragent@cursor.com>

WebApp/Components/Features/Students/Create.razor

@@ -31,6 +31,9 @@
             <MudItem xs="12" sm="6">
                 <MudTextField T="string" Label="Last Name" @bind-Value="Student.LastName" For="@(() => Student.LastName)" Variant="Variant.Outlined"></MudTextField>
             </MudItem>
+            <MudItem xs="12" sm="6">
+                <MudTextField T="string" Label="Nickname" @bind-Value="Student.Nickname" For="@(() => Student.Nickname)" Variant="Variant.Outlined" HelperText="Shown instead of first name on teams, rankings, and printouts"></MudTextField>
+            </MudItem>
             <MudItem xs="12" sm="6">
                 <MudTextField T="string" Label="Email Address" @bind-Value="Student.Email" For="@(() => Student.Email)" Variant="Variant.Outlined"></MudTextField>
             </MudItem>
@@ -80,6 +83,7 @@
 
         try
         {
+            Student.NormalizeNickname();
             Context.Students.Add(Student);
             await Context.SaveChangesAsync();