fix(xref): blocks respect their internal draw order

Xref merge now inserts entities in the source block's chain order and
carries SortEntitiesTable objects across (remapped to merged handles).
draw_depth_map values become [depth, half] so exploded block/xref fills
and wide-polyline band wires both compose child depth as
insert_depth + in-block rank x half, recursing into nested inserts with
the same divisor - bands and fills from one block interleave by the
block's internal order instead of stacking at the insert's single depth.
Band batches split per rank via WireModel.depth_override; thin wires
stay merged. The wire arena falls back to a full rebuild when a slab
carries mixed depths so refreshes don't flatten band overrides.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scene/pipeline/mod.rs

@@ -1477,7 +1477,7 @@ impl Pipeline {
         &self,
         device: &wgpu::Device,
         wires: &[WireModel],
-        depth_map: &rustc_hash::FxHashMap<u64, f32>,
+        depth_map: &rustc_hash::FxHashMap<u64, [f32; 2]>,
     ) -> (
         std::sync::Arc<Vec<WireGpu>>,
         std::sync::Arc<rustc_hash::FxHashMap<u64, Vec<u32>>>,
@@ -1543,7 +1543,7 @@ impl Pipeline {
         wires: &[WireModel],
         selected: &rustc_hash::FxHashSet<acadrust::Handle>,
         hover: Option<acadrust::Handle>,
-        depth_map: &rustc_hash::FxHashMap<u64, f32>,
+        depth_map: &rustc_hash::FxHashMap<u64, [f32; 2]>,
     ) {
         let hover = hover.filter(|h| !selected.contains(h));
         if selected.is_empty() && hover.is_none() {
@@ -1627,7 +1627,7 @@ impl Pipeline {
         &mut self,
         device: &wgpu::Device,
         wires: &[WireModel],
-        depth_map: &rustc_hash::FxHashMap<u64, f32>,
+        depth_map: &rustc_hash::FxHashMap<u64, [f32; 2]>,
     ) {
         self.gpu_preview_wires = if wires.is_empty() {
             vec![]
@@ -1912,7 +1912,7 @@ impl Pipeline {
         face3d_wires: &[WireModel],
         all_wires: &[WireModel],
         wireframe_only: bool,
-        depth_map: &rustc_hash::FxHashMap<u64, f32>,
+        depth_map: &rustc_hash::FxHashMap<u64, [f32; 2]>,
     ) {
         // Edge buffer is always built from `face3d_wires`, so 3DFACE
         // outlines stay on the screen regardless of mode.