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>

WebApp/Models/ChapterSettings.cs

@@ -1,4 +1,6 @@
 using Core.Models;
+using Core.Notes;
+using Microsoft.Extensions.Configuration;
 
 namespace WebApp.Models;
 
@@ -51,4 +53,26 @@ public class ChapterSettings
     /// School level for the chapter (null = import both MS and HS events)
     /// </summary>
     public SchoolLevel? SchoolLevel { get; set; }
+
+    /// <summary>
+    /// Field names from student note <c>## Imported fields</c> tables to show as Students index columns.
+    /// </summary>
+    public List<string> StudentIndexNoteFields { get; set; } = [.. StudentNoteFieldDefaults.IndexColumns];
+
+    public static ChapterSettings FromConfiguration(IConfiguration configuration)
+    {
+        var settings = configuration.GetSection("ChapterSettings").Get<ChapterSettings>()
+                       ?? new ChapterSettings();
+        settings.StudentIndexNoteFields = ReadIndexNoteFields(configuration);
+        return settings;
+    }
+
+    public static List<string> ReadIndexNoteFields(IConfiguration configuration)
+    {
+        var fields = configuration.GetSection("ChapterSettings:StudentIndexNoteFields").Get<List<string>>();
+        if (fields is null)
+            return [.. StudentNoteFieldDefaults.IndexColumns];
+
+        return [.. fields.Where(f => !string.IsNullOrWhiteSpace(f)).Select(f => f.Trim())];
+    }
 }