LAYOFF / LAYFRZ / LAYLCK / LAYON / LAYTHW / LAYULK / LAYISO /
LAYUNISO mutated the document's layer table (\`turn_off\` /
\`freeze\` / \`lock\` / …) and then called \`sync_ribbon_layers\`,
which feeds the ribbon dropdown from \`self.tabs[i].layers.layers\`
— the \`LayerPanel\` cache. That cache was never refreshed from
the document for these commands, so the dropdown stayed wrong and
the Layers Properties Manager kept showing the old visibility /
lock / freeze icons.
Add \`OpenCADStudio::refresh_layer_panel\` that runs
\`LayerPanel::sync_with_viewports\` from the live document before
calling \`sync_ribbon_layers\`. Replace every direct
\`sync_ribbon_layers\` in \`commands.rs\` (all of them sit inside
LAY* arms) with the new helper.
Closes#39
89fcb21b46