Components are frames (user bug #4)

What a component holds moves with its occurrence, and picks in the world land in the
component's frame:
- Sketches and construction planes show where their component is placed (free move, joint
  drive, Capture Position); sketch.inspect reports sketch points in the world.
- frames.rs maps a command's world picks into the frame of the body they lie on (through the
  inverse of its placement: a moved component or a pasted instance), points that make new
  geometry into the active component's frame, and directions with them; instance body names
  ("Body1 (Pin:2)") become the component's body. Fillet/chamfer edges, shell/offset/draft
  faces, face extrude/revolve, sketch on face, holes, sheet metal and plastic picks, primitives,
  appearance faces, analyses. Once per command (not again for commands run by commands); the
  active-frame fallback stays for commands without a table. Nothing changes while every
  placement is the identity.
- component.move_bodies keeps a body where it is in the world (Document.body_offsets: from the
  new component's frame to the one it was made in; renames and deleted components follow).
- The UI reads the placed model (Session::world_state) for display, picking, sketch editing and
  dialogs; live previews use it once anything is placed.
Tests (engine): sketches and construction planes move (and turn) with the component; world
picks fillet, sketch, hole and make boxes in a moved component; a pick on a pasted instance;
move_bodies keeps the world place there and back; a sketch on a face follows a Move feature.
QA's s34 now runs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/ui-egui/src/browser.rs

@@ -90,7 +90,7 @@ fn find_group(app: &SolveApp, id: u64) -> Option<&solvecraft_engine::doc::Browse
 
 /// The bodies in a group (none for sketch and plane groups).
 pub fn group_bodies(app: &SolveApp, id: u64) -> Vec<String> {
-    let st = app.session.model.state();
+    let st = app.session.world_state();
     find_group(app, id)
         .filter(|g| g.folder == "bodies")
         .map(|g| g.items.iter().filter(|b| st.body(b).is_some()).cloned().collect())
@@ -172,7 +172,7 @@ pub fn toggle_folder(app: &mut SolveApp, component: u64, folder: &str) {
 pub fn selection_group(app: &SolveApp, target: &Target) -> Option<Value> {
     let (comp, folder) = match target {
         Target::Body { name } => {
-            let st = app.session.model.state();
+            let st = app.session.world_state();
             let b = st.body(name)?;
             (app.session.doc.body_component(name, b.feature), "bodies")
         }