atdunbg
dec171cd1e
entt entity 0's integral bits are 0, colliding with the "no selection"
sentinel: u32 selected == 0 meant "clear selection", so the scene's
first-created entity could never be outlined. Replaced with
std::optional<u32> + FrameSceneData::selectedEntityValid.
Also restore per-batch instance contiguity broken by the batchMats
flattening (e038cb3): entities sharing a mesh scatter across the flat
instance array in collection order. ViewScratch now tracks per-batch
singly-linked lists and appendView aggregates each batch into a
contiguous range, preserving the flat-array performance intent.
Hierarchy click selection now routes through SelectEntity so outline
stays in sync when picking from the panel.