fix: EmailListModel as QAbstractTableModel for proper MailListView display

- Changed EmailListModel from QAbstractListModel to QAbstractTableModel
- Added columnCount() returning 3 columns (Subject, Sender, Date)
- Added headerData() for column headers (Asunto, De, Fecha)
- Modified data() to handle Qt::DisplayRole per column index
- Updated MailListView::setModel() to use column indices instead of role-based column hiding
- Added proper column resize modes (Stretch for Subject/Sender, ResizeToContents for Date)
- Default sort by Date column descending

src/ui/models/EmailListModel.h

@@ -1,12 +1,12 @@
 #ifndef EMAILLISTMODEL_H
 #define EMAILLISTMODEL_H
 
-#include <QAbstractListModel>
+#include <QAbstractTableModel>
 #include <QHash>
 #include <QByteArray>
 #include "../db/dao/mailitemdao.h"
 
-class EmailListModel : public QAbstractListModel
+class EmailListModel : public QAbstractTableModel
 {
     Q_OBJECT
 public:
@@ -28,8 +28,18 @@ public:
         SenderInitialRole // computed from sender
     };
 
+    // Column indices (match role order for simplicity)
+    enum Columns {
+        ColSubject = 0,
+        ColSender = 1,
+        ColDate = 2,
+        ColCount = 3 // number of visible columns
+    };
+
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+    int columnCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+    QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
     QHash<int, QByteArray> roleNames() const override;
 
     // Set the folderId to filter emails; -1 means all folders
@@ -40,7 +50,5 @@ public:
 private:
     QVector<MailItem> m_emails;
     int m_folderId{-1}; // -1 means all folders
-    // REMOVED: MailItemDao& m_mailItemDao; // Methods are static, no instance needed
 };
-
 #endif // EMAILLISTMODEL_H