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/timeline.rs

@@ -112,7 +112,7 @@ pub fn timeline(app: &mut SolveApp, ui: &mut egui::Ui) {
             .map(|f| (f.id, f.name.clone(), icon_of(&f.kind), f.suppressed, f.kind.type_name(), f.kind.clone()))
             .collect();
         // The feature whose body is under the cursor in the viewport.
-        let st = app.session.model.state();
+        let st = app.session.world_state();
         let from_view = match &app.viewport.hover {
             Some(crate::viewport::Hit::Face { body, .. } | crate::viewport::Hit::Edge { body, .. } | crate::viewport::Hit::Vertex { body, .. }) => {
                 st.body(body).map(|b| b.feature)
@@ -298,7 +298,7 @@ pub fn timeline(app: &mut SolveApp, ui: &mut egui::Ui) {
 
 /// Select what a feature made, so the browser shows it.
 fn find_in_browser(app: &mut SolveApp, id: u64) {
-    let st = app.session.model.state();
+    let st = app.session.world_state();
     let bodies: Vec<serde_json::Value> = st.bodies.iter().filter(|b| b.feature == id).map(|b| json!({"type": "body", "name": b.name})).collect();
     let items = if bodies.is_empty() { vec![json!({"type": "feature", "id": id})] } else { bodies };
     let _ = app.run("select.set", json!({ "items": items }));