fix(tui): enable right-click copy anywhere when text is selected (#355)

Previously, right-click copy only worked when clicking within a registered
click zone. This fix ensures that when text is selected (via left-click drag),
right-clicking anywhere on the screen will copy the selected text to clipboard.

This matches the expected behavior in terminal emulators where right-click
should copy selected text regardless of where the click lands.

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt

cortex-tui/src/runner/event_loop.rs

@@ -8778,6 +8778,15 @@ impl EventLoop {
                     }
                 }
 
+                // Right-click with selection: always copy, regardless of click zone
+                // This enables right-click to copy anywhere on screen when text is selected
+                if button == MouseButton::Right && self.app_state.text_selection.has_selection() {
+                    self.copy_selection_to_clipboard(terminal)?;
+                    self.app_state.text_selection.clear();
+                    self.render(terminal)?;
+                    return Ok(());
+                }
+
                 // Handle clicks in Questions view
                 if self.app_state.view == AppView::Questions
                     && button == MouseButton::Left