V2.5.1 — Dialogue licence custom + fix recadrage + style

- Dialogue de licence custom (remplace QInputDialog moche)
  - Logo CopyDev, champ stylise, bouton Activer cyan
  - Messages erreur/succes en dialogues custom colores
- Fix recadrage : reference au dialogue preservee avant destruction
- Splash screen sans bordure carree
- Style coherent gris/cyan sur tous les dialogues

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/main_window.py

@@ -714,16 +714,27 @@ class MainWindow(QMainWindow):
         )
 
         def on_crop_accepted():
+            if not hasattr(self, '_crop_dlg') or not self._crop_dlg:
+                return
+            dlg_ref = self._crop_dlg
+            self._crop_dlg = None
+            try:
+                settings = dlg_ref.get_settings()
+            except Exception:
+                return
+            if not settings.get("pages"):
+                return
             self._show_progress()
-            settings = self._crop_dlg.get_settings()
             output = self._make_temp()
             try:
                 crop_pages(self._current_file, output, **settings)
                 self._show_result(output)
+                self._status_label.setText(
+                    f"Recadrage applique — {len(settings['pages'])} page(s)"
+                )
             except Exception as e:
                 self._hide_progress()
                 QMessageBox.critical(self, "Erreur", str(e))
-            self._crop_dlg = None
 
         self._crop_dlg.accepted.connect(on_crop_accepted)
         self._crop_dlg.rejected.connect(lambda: setattr(self, '_crop_dlg', None))