fix(settings): stabilize navigation hover state

[Tryanks]

Summary

• keep the settings navigation hitbox, stable element ID, hover style, and click handler on the same GPUI element
• align settings navigation rows with the proven main-sidebar row structure

Root cause

The accessible clickable wrapper and its anonymous hover-painted child created two overlapping interaction regions, allowing hover paint to become stale or skip while crossing adjacent tabs.

Verification

• cargo check -p tcode-ui
• cargo test -p tcode-ui (300 passed)
• cargo fmt --all --check
• git diff --check