added a "Selected Compounds" box at the left of the canvas.

[shubham148-st]

Feature: Add Selected Compounds Panel to simulation GUI

This PR introduces a new "Selected Compounds" box (dock widget) on the left side of the canvas. It displays the list of selected chemical compounds in real time as the user selects them.

Key Changes:

1. Real-time Signal in Compound Selector (ComponentSelector.py):

compounds will be visible as we check and unchecked it in the select compounds menu. Simply, visibility of compunds toggles in the new box, removed compounds gets invisible while selected ones stay.

2. Left Dock Widget Integration (mainApp.py):

Added a QDockWidget (box) on the left side of the canvas.

3. View Menu Integration (mainApp.py):

toggle the visibility of the new box.

4. refresh function(mainApp.py):

extracts the compounds from the backend.