feat: add a Tools page printer for note merge and print presets

Chapter officers can merge a markdown note onto filtered students, teams, or events and save the recipe. Extra student-note columns are additional fields (any ## … fields heading) so they work as print tokens whether imported or typed by hand.

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

Core/Printing/NoteTemplateMerger.cs

@@ -0,0 +1,73 @@
+using System.Text.RegularExpressions;
+
+namespace Core.Printing;
+
+/// <summary>
+/// Replaces <c>{{Token}}</c> placeholders from a case-insensitive map.
+/// Unknown tokens are left unchanged. Known empty values become blank.
+/// <c>{{PageBreak}}</c> becomes a print page break after HTML conversion.
+/// <c>{{AnswerSpace}}</c> becomes ruled write-in space after HTML conversion.
+/// </summary>
+public static class NoteTemplateMerger
+{
+    public const string PageBreakToken = "PageBreak";
+    public const string PageBreakSentinel = "<!--tsa-page-break-->";
+    public const string PageBreakHtml = "<div class=\"pagebreak\"></div>";
+
+    public const string AnswerSpaceToken = "AnswerSpace";
+    public const string AnswerSpaceSentinel = "<!--tsa-answer-space-->";
+    public const string AnswerSpaceHtml = "<div class=\"print-answer-space\"></div>";
+
+    private readonly record struct LayoutToken(string Name, string Sentinel, string Html);
+
+    private static readonly LayoutToken[] LayoutTokens =
+    [
+        new(PageBreakToken, PageBreakSentinel, PageBreakHtml),
+        new(AnswerSpaceToken, AnswerSpaceSentinel, AnswerSpaceHtml)
+    ];
+
+    private static readonly Regex TokenRegex = new(@"\{\{([^}]+)\}\}", RegexOptions.Compiled);
+
+    public static string Merge(string? template, IReadOnlyDictionary<string, string> tokens)
+    {
+        if (string.IsNullOrEmpty(template))
+            return string.Empty;
+
+        ArgumentNullException.ThrowIfNull(tokens);
+
+        return TokenRegex.Replace(template, match =>
+        {
+            var key = match.Groups[1].Value.Trim();
+            if (key.Length == 0)
+                return match.Value;
+
+            foreach (var layout in LayoutTokens)
+            {
+                if (key.Equals(layout.Name, StringComparison.OrdinalIgnoreCase))
+                    return layout.Sentinel;
+            }
+
+            return tokens.TryGetValue(key, out var value)
+                ? value ?? string.Empty
+                : match.Value;
+        });
+    }
+
+    /// <summary>
+    /// Turns layout sentinels into HTML after markdown has been rendered.
+    /// </summary>
+    public static string ApplyLayout(string? html)
+    {
+        if (string.IsNullOrEmpty(html))
+            return string.Empty;
+
+        foreach (var layout in LayoutTokens)
+        {
+            html = html
+                .Replace($"<p>{layout.Sentinel}</p>", layout.Html, StringComparison.Ordinal)
+                .Replace(layout.Sentinel, layout.Html, StringComparison.Ordinal);
+        }
+
+        return html;
+    }
+}