Solids (meshes) now tint on rollover and selection: hover washes orange,
selection washes blue, with selection winning when both apply. Meshes
re-upload their tint when the highlight set changes, and the rollover pick
now also hits shaded solid bodies and hatches (mirroring the click-select
order: wire → hatch → block hatch → solid).
Wires get the same scheme: the selection xray overlay recolours selected
entities blue and the hovered entity orange (previously both blue). Drops
the now-unused highlight_handles union helper and its cache.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>