fix(zoom): fit 3D solids in ZOOM EXTENTS (fit_all)

ZOOM EXTENTS routes through fit_all, which built its bounds from the
wire set and returned early when there were none. A drawing of only 3D
solids has no wires, so ZOOM EXTENTS did nothing. Collect the
layout's mesh AABBs alongside the wires, keep going when only meshes
exist, and fold them into the fitted bounds.

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

src/scene/mod.rs

@@ -5703,7 +5703,21 @@ impl Scene {
         if self.current_layout != "Model" {
             wires.extend(self.viewport_content_wires(layout_block, None, None));
         }
-        if wires.is_empty() {
+        // 3D solids render as meshes, not wires, so collect their (offset-rel)
+        // XY AABBs separately — a drawing of only solids has no wires to fit.
+        let mesh_aabbs: Vec<[f32; 4]> = self
+            .meshes
+            .iter()
+            .filter(|(h, _)| {
+                self.document
+                    .get_entity(**h)
+                    .map(|e| e.common().owner_handle == layout_block)
+                    .unwrap_or(false)
+            })
+            .map(|(_, set)| set.world_aabb)
+            .filter(|a| a[0].is_finite() && a[2].is_finite())
+            .collect();
+        if wires.is_empty() && mesh_aabbs.is_empty() {
             return;
         }
 
@@ -5743,7 +5757,7 @@ impl Scene {
                 });
             }
         }
-        if cents.is_empty() {
+        if cents.is_empty() && mesh_aabbs.is_empty() {
             return;
         }
 
@@ -5791,6 +5805,11 @@ impl Scene {
                 max = max.max(glam::Vec3::new(x, y, z));
             }
         }
+        // Fold in 3D-solid mesh AABBs (not subject to the wire IQR reject).
+        for [ax, ay, bx, by] in &mesh_aabbs {
+            min = min.min(glam::Vec3::new(*ax, *ay, 0.0));
+            max = max.max(glam::Vec3::new(*bx, *by, 0.0));
+        }
         // If no usable points found, leave the camera unchanged.
         if min.x > max.x {
             return;