Two zones — sidebar and body — with vim-style bindings:
sidebar j/Down next category
k/Up previous category
l/Right/Tab/Enter/Ctrl-L enter body
Esc close panel
body j/Down/Tab next focusable
k/Up/Shift-Tab previous focusable
Enter/Space activate focused control
h/Left/Esc/Ctrl-H back to sidebar
Wraps panel content in a FocusScope with Keys.priority: Keys.BeforeItem
so j/k always reach the nav handler even when a child control has focus.
Body focusables are gathered by walking the visible subtree of the active
category for items with activeFocusOnTab — automatically excluding
hidden category branches. Sidebar shows an accent-tinted highlight when
focused; each interactive control (DefaultsRow, StyleOptionTile,
StyleChip, FontRow, StyleToggleRow, ActionPill, IconButton, PluginRow)
renders an accent focus ring while focused.