feat(lwpolyline): render the wide-polyline band via the wire shader

A wide polyline's flat band was drawn by the hatch pipeline: a solid fill
with only draw-order depth. It ignored the entity linetype (the width
"crushed" the dash pattern) and showed through 3-D geometry in a tilted view.

Draw the band from the polyline's own centre-line wire instead. A new
`WireModel.world_width` (drawing units) makes the wire vertex shader expand
the quad by `world_half_width / world_per_pixel` (clamped to a hairline), so
the band is sized in world units and tracks zoom. Because it is now a wire:

- the GPU dash shader dashes the band by arc-length — the linetype applies;
- it is depth-tested at the polyline elevation — no draw-order see-through;
- no CPU band triangles or per-dash geometry are generated.

`world_half_width` rides in `WireConst` (native, replacing a pad) and the web
`WireInstance` (loc 14); both wire shaders branch on it. The tessellator sets
`world_width` from the LwPolyline width on the Contour / SegmentedLines arms,
and the model-space fill loop no longer emits a hatch band for any LwPolyline.
Pick still uses the band polygon (`pick_tris`).

Blocks keep the hatch band: `LocalWire` carries no `world_width` (finalize
zeroes it), so a scaled insert still scales its band correctly.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/modules/draw/draw/attdef.rs

@@ -160,6 +160,7 @@ impl CadCommand for AttdefCommand {
         // Show a small cross at the insertion point.
         let d = 0.15_f32;
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/draw/mline.rs

@@ -136,6 +136,7 @@ impl CadCommand for MlineCommand {
             .collect();
         pts.push([pt.x, pt.y, pt.z]);
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/draw/raster_image.rs

@@ -108,6 +108,7 @@ impl CadCommand for ImageCommand {
         let p3 = [origin.x, origin.y + world_height, origin.z];
 
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/draw/ray.rs

@@ -84,6 +84,7 @@ impl CadCommand for RayCommand {
         let dir = (pt - base).normalize_or_zero();
         let far = base + dir * DISPLAY_EXTENT;
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),
@@ -179,6 +180,7 @@ impl CadCommand for XLineCommand {
         let far_pos = base + dir * DISPLAY_EXTENT;
         let far_neg = base - dir * DISPLAY_EXTENT;
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/draw/revcloud.rs

@@ -89,6 +89,7 @@ impl CadCommand for RevCloudCommand {
             self.points[0].z as f32,
         ]);
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/draw/wipeout.rs

@@ -114,6 +114,7 @@ impl CadCommand for WipeoutCommand {
                 let min = p1.min(pt);
                 let max = p1.max(pt);
                 Some(WireModel {
+                    world_width: 0.0,
                     fill_is_3d: false,
                     pick_tris: Vec::new(),
                     pick_tris_low: Vec::new(),
@@ -160,6 +161,7 @@ impl CadCommand for WipeoutCommand {
                     self.poly_pts[0].z as f32,
                 ]);
                 Some(WireModel {
+                    world_width: 0.0,
                     fill_is_3d: false,
                     pick_tris: Vec::new(),
                     pick_tris_low: Vec::new(),

src/modules/draw/inquiry/area.rs

@@ -69,6 +69,7 @@ impl CadCommand for AreaCommand {
         pts.push(f(pt));
         pts.push(f(self.points[0]));
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/inquiry/dist.rs

@@ -63,6 +63,7 @@ impl CadCommand for DistCommand {
         let p1 = self.first?;
         // The preview wire is purely visual, so f32 vertices are fine here.
         Some(WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/inquiry/measuregeom.rs

@@ -67,6 +67,7 @@ impl MeasureGeomCommand {
     /// Build a cyan preview wire connecting the picked points and the cursor.
     fn preview_wire(name: &str, pts: Vec<[f32; 3]>) -> WireModel {
         WireModel {
+            world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
             pick_tris_low: Vec::new(),

src/modules/draw/modify/trim.rs

@@ -3059,6 +3059,7 @@ fn collect_runs(pts: &[[f64; 2]], take: &dyn Fn([f64; 2]) -> bool, out: &mut Vec
 /// Build a preview wire from a NaN-break point list.
 fn preview_wire(points: Vec<[f32; 3]>, color: [f32; 4], name: &str) -> WireModel {
     WireModel {
+        world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),
         pick_tris_low: Vec::new(),