Distribution_GL Initialization

Services/CsvDocuments/CsvBuilder.cs

@@ -0,0 +1,46 @@
+using System.Globalization;
+using System.Text;
+
+namespace General_Ledger_Service.Services.CsvDocuments
+{
+    // Shared row-building/escaping helper for every report's CSV writer (05_LKAS_Report_PDF_Templates.md
+    // Section 10) - parallel to Services/PdfDocuments/ReportPageHeader.cs, one small shared piece
+    // reused by seven otherwise-independent writer classes, not a base class (CLAUDE.md Rule 2).
+    public class CsvBuilder
+    {
+        private readonly StringBuilder _sb = new();
+
+        public CsvBuilder AddRow(params object?[] values)
+        {
+            _sb.AppendLine(string.Join(",", values.Select(Escape)));
+            return this;
+        }
+
+        public byte[] Build()
+        {
+            // UTF-8 BOM so Excel (the realistic consumer of a downloaded .csv) recognizes the
+            // encoding instead of guessing at a locale-default codepage.
+            var preamble = Encoding.UTF8.GetPreamble();
+            var body = Encoding.UTF8.GetBytes(_sb.ToString());
+            var result = new byte[preamble.Length + body.Length];
+            preamble.CopyTo(result, 0);
+            body.CopyTo(result, preamble.Length);
+            return result;
+        }
+
+        private static string Escape(object? value)
+        {
+            var text = value switch
+            {
+                null => "",
+                decimal d => d.ToString(CultureInfo.InvariantCulture),
+                DateOnly d => d.ToString("yyyy-MM-dd"),
+                _ => value.ToString() ?? ""
+            };
+
+            return text.Contains(',') || text.Contains('"') || text.Contains('\n')
+                ? $"\"{text.Replace("\"", "\"\"")}\""
+                : text;
+        }
+    }
+}