feat: responsive compact mail view + folder unread badges

- CompactMailDelegate: card-based view for narrow panels (<420px)
  * Avatar with hash-based color, sender + date (relative format)
  * Subject line with attachment icon
  * Action buttons: flag, delete, category, more (context menu)
  * Unread highlight with light blue background + bold sender
- MailListView: automatic switch between tree/table (wide) and list/cards (narrow)
  * QStackedWidget with QTreeView + QListView sharing same proxy model
  * resizeEvent threshold at 420px
  * Signals forwarded to MainMainWindow for actions
- FolderTreeDelegate: custom paint for folder tree
  * Unread count badge (blue pill) right-aligned on folder nodes
  * Account nodes bold, folder nodes normal weight
  * Proper indentation per depth level
- MailItemDao::countUnreadByFolderId() for real-time unread counts
- MainMainWindow handlers for compact actions (flag, delete, category, more menu)

add_include.py

@@ -0,0 +1,15 @@
+import sys
+
+filename = '/mnt/c/Users/javie/wino-mail-dtkqt/src/ui/mainmainwindow.cpp'
+with open(filename, 'r') as f:
+    lines = f.readlines()
+
+for i, line in enumerate(lines):
+    if '#include "ui/models/emaillistmodel.h"' in line:
+        lines.insert(i+1, '#include "ui/maillistview.h"\n')
+        break
+
+with open(filename, 'w') as f:
+    f.writelines(lines)
+
+print('Added include')