chore: release v2.4

- Add theme system (Dark/Light palettes, ModernTheme, ThemeManager)
- Add InputDialog, Spinner common view
- Add DuplicatesCsvExportService
- Refresh views, dialogs, and view models across tabs
- Update localization strings (en/fr)
- Tweak services (transfer, permissions, search, user access, ownership elevation, bulk operations)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

SharepointToolbox/Services/Export/SearchCsvExportService.cs

@@ -1,6 +1,7 @@
 using System.IO;
 using System.Text;
 using SharepointToolbox.Core.Models;
+using SharepointToolbox.Localization;
 
 namespace SharepointToolbox.Services.Export;
 
@@ -10,12 +11,17 @@ namespace SharepointToolbox.Services.Export;
 /// </summary>
 public class SearchCsvExportService
 {
+    /// <summary>
+    /// Builds the CSV payload. Column order mirrors
+    /// <see cref="SearchHtmlExportService.BuildHtml(IReadOnlyList{SearchResult}, ReportBranding?)"/>.
+    /// </summary>
     public string BuildCsv(IReadOnlyList<SearchResult> results)
     {
+        var T = TranslationSource.Instance;
         var sb = new StringBuilder();
 
         // Header
-        sb.AppendLine("File Name,Extension,Path,Created,Created By,Modified,Modified By,Size (bytes)");
+        sb.AppendLine($"{T["report.col.file_name"]},{T["report.col.extension"]},{T["report.col.path"]},{T["report.col.created"]},{T["report.col.created_by"]},{T["report.col.modified"]},{T["report.col.modified_by"]},{T["report.col.size_bytes"]}");
 
         foreach (var r in results)
         {
@@ -33,19 +39,14 @@ public class SearchCsvExportService
         return sb.ToString();
     }
 
+    /// <summary>Writes the CSV to <paramref name="filePath"/> with UTF-8 BOM.</summary>
     public async Task WriteAsync(IReadOnlyList<SearchResult> results, string filePath, CancellationToken ct)
     {
         var csv = BuildCsv(results);
-        await System.IO.File.WriteAllTextAsync(filePath, csv, new UTF8Encoding(encoderShouldEmitUTF8Identifier: true), ct);
+        await ExportFileWriter.WriteCsvAsync(filePath, csv, ct);
     }
 
-    private static string Csv(string value)
-    {
-        if (string.IsNullOrEmpty(value)) return string.Empty;
-        if (value.Contains(',') || value.Contains('"') || value.Contains('\n'))
-            return $"\"{value.Replace("\"", "\"\"")}\"";
-        return value;
-    }
+    private static string Csv(string value) => CsvSanitizer.EscapeMinimal(value);
 
     private static string IfEmpty(string? value, string fallback = "")
         => string.IsNullOrEmpty(value) ? fallback : value!;