DT: semsubstr, click node → open popup like nodelink

BCK ID: BCK-528

Priority: High

Type: Feature

Description: In semantic substrates visualization, when clicking a node, open a popup similar to the one in nodelink visualization.

Requirements:

• Implement node click handler in semantic substrates
• Display popup with node information (similar to nodelink)
• Ensure consistent UX between visualizations

Asana Task: https://app.asana.com/1/1206648675960041/project/1208204369345947/task/1210638405735852