feat: add delete page functionality

- Added 'Delete Page' option to Edit menu
- Implemented deletion logic in MainWindow, removing page from service and refreshing UI
- Ensures changes are marked as modified for saving

src/teletext/ui.py

@@ -330,6 +330,10 @@ class MainWindow(QMainWindow):
         paste_action.triggered.connect(self.paste_page_content)
         edit_menu.addAction(paste_action)
         
+        delete_page_action = QAction("Delete Page", self)
+        delete_page_action.triggered.connect(self.delete_page)
+        edit_menu.addAction(delete_page_action)
+        
         edit_menu.addSeparator()
         
         undo_action = QAction("Undo", self)
@@ -524,6 +528,36 @@ class MainWindow(QMainWindow):
         # So I need to refactor paste_page_content to call push_undo_state() first.
         # For now, I'll add the methods here.
 
+    def delete_page(self):
+        if not self.current_page:
+            return
+            
+        ret = QMessageBox.question(self, "Delete Page", 
+                                   f"Are you sure you want to delete Page {self.current_page.full_page_number} (Sub {self.current_page.sub_code:04X})?",
+                                   QMessageBox.StandardButton.Yes | QMessageBox.StandardButton.No)
+                                   
+        if ret == QMessageBox.StandardButton.Yes:
+            # Remove from service.pages
+            if self.current_page in self.service.pages:
+                self.service.pages.remove(self.current_page)
+                
+            # Remove packets from all_packets
+            # This is important for saving cleanly
+            # Filter out packets that belong to this page instance
+            # Note: We rely on object identity or need robust tracking. 
+            # Since we reconstruct all_packets on save from pages, we don't strictly need to prune all_packets NOW,
+            # but it's good practice or we can just rely on save_file's reconstruction logic.
+            # save_file logic:
+            # new_all_packets = []
+            # for page in self.service.pages: ...
+            # So removing from service.pages is sufficient for the next Save.
+            
+            self.set_modified(True)
+            self.current_page = None
+            self.canvas.set_page(None)
+            self.populate_list()
+            self.status_label.setText("Page deleted.")
+
     def push_undo_state(self):
         if not self.current_page: return
         # Push deep copy of current page