Add drag&drop .asm preview and force CSV output to repo root

Fase 5 now shows the distinta's .asm files already copied to raw/ as
draggable icons, so they can be dropped straight onto Creo or Explorer
without re-hitting the DB/share. The CSV from fase 2 is now always
written to the repo root (found by walking up to CLAUDE.md) instead of
next to the input file, wherever that happens to be.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

CadSearchGui/DistintaBaseImporter.cs

@@ -25,7 +25,8 @@ static class DistintaBaseImporter
         Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);
     }
 
-    public static (string PercorsoCsv, List<(string Componente, string Descrizione)> Righe) ConvertiInCsv(string percorsoInput)
+    public static (string PercorsoCsv, List<(string Componente, string Descrizione)> Righe) ConvertiInCsv(
+        string percorsoInput, string? cartellaOutput = null)
     {
         var righeGrezze = EImmagineSpreadsheetMl(percorsoInput)
             ? LeggiRigheSpreadsheetMl(percorsoInput)
@@ -44,7 +45,7 @@ static class DistintaBaseImporter
         }
 
         var percorsoCsv = Path.Combine(
-            Path.GetDirectoryName(Path.GetFullPath(percorsoInput))!,
+            cartellaOutput ?? Path.GetDirectoryName(Path.GetFullPath(percorsoInput))!,
             Path.GetFileNameWithoutExtension(percorsoInput) + ".csv");
 
         using var writer = new StreamWriter(percorsoCsv, false, Encoding.UTF8);