fix: convert grip positions to local space for display and hit-test

Entity grips() return world-space coordinates (raw DXF values). After
the world_offset change the camera view_proj is in local space, so
projecting world-space grips through it gave wrong screen positions and
hit-test failures.

- refresh_selected_grips: subtract world_offset from every grip.world
  so selected_grips are stored in local (camera) space
- Grip drag: cursor/snap positions are already local space; for
  GripApply::Absolute add world_offset back before passing to entity
  so entity coordinates stay in world space. Translate deltas are
  identical in both spaces so no conversion is needed there.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/properties.rs

@@ -244,11 +244,20 @@ impl H7CAD {
     /// Rebuild the cached selected_grips from the current entity selection.
     pub(super) fn refresh_selected_grips(&mut self) {
         let i = self.active_tab;
+        let wo = self.tabs[i].scene.world_offset;
         let (new_handle, new_grips) = {
             let selected = self.tabs[i].scene.selected_entities();
             if selected.len() == 1 {
                 let (handle, entity) = selected[0];
-                let grips = dispatch::grips(entity);
+                let grips = dispatch::grips(entity)
+                    .into_iter()
+                    .map(|mut g| {
+                        g.world.x -= wo[0] as f32;
+                        g.world.y -= wo[1] as f32;
+                        g.world.z -= wo[2] as f32;
+                        g
+                    })
+                    .collect();
                 (Some(handle), grips)
             } else {
                 (None, vec![])

src/app/update.rs

@@ -1133,10 +1133,12 @@ impl H7CAD {
                         }
                     }
 
+                    let wo = self.tabs[i].scene.world_offset;
+                    let wo_vec = glam::Vec3::new(wo[0] as f32, wo[1] as f32, wo[2] as f32);
                     let apply = if grip.is_translate {
                         GripApply::Translate(snapped - grip.last_world)
                     } else {
-                        GripApply::Absolute(snapped)
+                        GripApply::Absolute(snapped + wo_vec)
                     };
                     self.tabs[i].scene.apply_grip(grip.handle, grip.grip_id, apply);
                     self.tabs[i].dirty = true;