feat: import leftover student fields into notes and show them on the roster

Store leftover CSV columns on hidden student notes, move catalog import to /events/import, and persist Students index columns from Chapter Settings.

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

Tests/Services/NoteNamingService_Tests.cs

@@ -0,0 +1,28 @@
+using Core.Services;
+
+namespace Tests.Services;
+
+[TestFixture]
+public class NoteNamingService_Tests
+{
+    private readonly NoteNamingService _service = new();
+
+    [Test]
+    public void GetStudentNoteTitle_UsesStablePrefix()
+    {
+        Assert.That(_service.GetStudentNoteTitle(42), Is.EqualTo("#Student:42"));
+    }
+
+    [Test]
+    public void IsStudentNote_AndParseId()
+    {
+        Assert.That(_service.IsStudentNote("#Student:12"), Is.True);
+        Assert.That(_service.IsStudentNote("#Students"), Is.False);
+        Assert.That(_service.TryParseStudentNoteId("#Student:12", out var id), Is.True);
+        Assert.That(id, Is.EqualTo(12));
+        Assert.That(_service.TryParseStudentNoteId("#Event Ranking", out _), Is.False);
+        Assert.That(_service.IsStudentNote(null), Is.False);
+        Assert.That(_service.TryParseStudentNoteId("#Student:", out _), Is.False);
+        Assert.That(_service.IsPageNote("#Student:12"), Is.True);
+    }
+}