Tree vertical nesting lines

Problem

Currently, nested items in trees (e.g., folders, views) don’t have vertical guide lines. This makes hierarchy harder to read and understand, especially in deep structures. Users struggle to visually parse nesting levels.

Expected

• Add vertical connector lines to tree components.

• Clearly show hierarchy depth, similar to standard file explorers (Finder, Explorer, IDEs).

• Ensure lines are subtle but visible in both light and dark modes.