Tabs' Context Menu

[sendevent]

This PR introduces a tab's RMB-click menu with dynamically available actions for copying file location info and advanced closing options:

• Right-click: activates the selected tab and opens a persistent context menu.
• Copy File Name: Copies the file name of the clicked tab, if available.
• Copy File Path: Copies the absolute file path of the clicked tab, if available.
• Close: Closes the clicked tab.
• Close All Tabs: Closes all tabs; enabled if 2+ tabs are open.
• Close Other Tabs: Closes all tabs except the clicked one; enabled if 2+ tabs are open.
• Close Unmodified Tabs: Closes tabs with no unsaved changes; enabled if 2+ tabs are open.
• Close Tabs to the Left/Right: Closes all tabs in the specified direction; enabled if 2+ tabs are open and the clicked one is not at the edge.