style: Remove dashed window border in split view

src/main_ncurses.cpp

@@ -1073,21 +1073,6 @@ private:
         if (show_modeline) {
             render_window_modeline(window, x, y + content_height, width, is_active);
         }
-        
-        // Draw window border if there are multiple windows
-        if (is_active && core_->root_layout()->type != LayoutNode::Type::Leaf) {
-            // Draw a simple border around the active window
-            attron(A_BOLD);
-            // Top border
-            move(y, x);
-            for (int i = 0; i < width; ++i) addch('-');
-            // Bottom border  
-            if (y + height < height_ - 2) {
-                move(y + height, x);
-                for (int i = 0; i < width; ++i) addch('-');
-            }
-            attroff(A_BOLD);
-        }
     }
     
     void render_window_modeline(std::shared_ptr<Window> window, int x, int y, int width, bool is_active) {