feat(xclip): clip block references to their SPATIAL_FILTER boundary

Block references carrying an XCLIP spatial filter were drawn in full,
ignoring the clip boundary. Resolve the filter through the INSERT's
extension dictionary (ACAD_FILTER -> SPATIAL) and clip the expanded
block geometry to the boundary polygon: polylines are split into the
inside runs, fill triangles are clipped, and snap/key vertices outside
the boundary are dropped.

The boundary vertices live in the clip-definition space, so they are
placed with world = T_insert * (inverse_block_transform * vert); this
keeps the clip correct even when the insert was rescaled after the clip
was created. Bumps acadrust to the build that decodes SPATIAL_FILTER.

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

src/scene/mod.rs

@@ -34,6 +34,7 @@ pub mod transform;
 pub mod truck_tess;
 pub mod viewport_pane;
 pub mod wire_model;
+pub mod xclip;
 
 use camera::Camera;
 pub use camera::Projection;
@@ -7327,6 +7328,14 @@ fn tessellate_entity(
                 is_xref,
                 bg_color,
             ) {
+                // XCLIP: if this INSERT carries an enabled spatial filter,
+                // clip the expanded block geometry to the boundary polygon so
+                // only the portion inside the clip is drawn.
+                if let Some(sf) = xclip::insert_spatial_filter(document, ins) {
+                    let poly = xclip::world_clip_polygon(sf, ins, world_offset);
+                    xclip::clip_wires(&mut wires, &poly);
+                }
+
                 // Per-INSERT attribute values. The block defn carries the
                 // AttributeDefinitions (templates) which expand_insert skips;
                 // the AttributeEntity instances live on the Insert itself in