feat(doc): persistent names follow the kernel's exact face history (#136)

Why: every reference a user makes to a face or edge (fillet and chamfer
edges, sketches on faces, shell/draft/offset faces, joints, appearances)
is stored as a name and found again after any upstream edit. Those names
were re-derived by sampling points of each face and voting, and pieces
of a split face were numbered by where their centres lay. After an
upstream edit that splits, merges, mirrors or shrinks a face, a fillet
or sketch could silently re-attach to the wrong face, and nothing told
the user. The kernel now reports exact history for its operations, so
names follow it and fail loudly instead of guessing.

- crates/doc/src/lineage.rs: a feature's kernel histories composed into
  one lineage over nameable operands (bodies before the feature, moved
  copies, shell cavities, tools named by role: sketch curve, cap, box
  side, imported face). Instrumented: extrude/revolve/sweep/loft tools,
  join/cut/intersect, lumps after a cut, fillet/chamfer, shell, draft,
  split face/body, pattern/mirror (bodies and features), combine,
  boundary fill, move/scale, offset/delete face, thread, import.
- crates/doc/src/history_names.rs: names from lineage; split pieces told
  apart by the faces only they touch (F2:top#[F2:side:l4,F4:side:l4]),
  merged faces answer to every name (aliases), lump bodies ordered by
  their faces' names instead of shell order.
- crates/doc/src/name_lookup.rs, piece_names.rs: references resolve by
  exact name, alias or bounding faces, else nearest piece with a
  warning; names worked out from geometry (operations without history)
  are reported when only geometry decided.
- Format 14: names stored by older formats get a legacy mark and are
  found as the build that saved them found them (some geometric names
  name a face history names differently: a tube's outer wall was named
  after its inner circle). New corpus file saved by 9a979cf.
- kernel: Body::lumps carries each piece's history over the whole.
- Adversarial tests: split, merge, mirrored twins, shrink to a sliver,
  moving cut with body pieces, history-less bodies, certified sketch.
- docs/book/src/dev/naming.md describes the real mechanism and why.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J53sR6gEaVt56soFDpTck8

apps/solvecraft-cli/tests/design_corpus.rs

@@ -90,6 +90,26 @@ fn old_designs_open_and_evaluate_as_saved() {
     assert!(problems.is_empty(), "{}", problems.join("\n"));
 }
 
+/// Names saved before format 14 were worked out from geometry, pieces of a split face numbered by
+/// where their centres lay (`F2:top#2`). They keep naming the faces they named: marked as such,
+/// they are found as the build that saved them found them, without new notes.
+#[test]
+fn names_saved_before_exact_history_find_the_faces_they_named() {
+    let path = Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/corpus/naming-split-pieces.solvecraft");
+    let s = open(&path);
+    let feature = |name: &str| s.doc.features.iter().find(|f| f.name == name).unwrap_or_else(|| panic!("{name}"));
+    assert_eq!(feature("Round").edge_names, vec!["?F2:side:l2|F2:top#2".to_string()]);
+    assert_eq!(feature("Bevel").edge_names, vec!["?F2:side:l4|F2:top#1".to_string()]);
+    assert_eq!(feature("Raise").face_names, vec!["?F2:top#1".to_string()]);
+    for r in &s.model.results {
+        assert!(r.error.is_none() && r.warning.is_none(), "{}: {:?} {:?}", r.name, r.error, r.warning);
+    }
+    // The raised piece is the left one, as saved (the stored point is on it).
+    let state = s.model.state();
+    let solid = |p: [f64; 3]| state.bodies.iter().any(|b| b.body.contains(solvecraft_engine::geom::Vec3::new(p[0], p[1], p[2])));
+    assert!(solid([7.0, 15.0, 11.0]) && !solid([32.0, 15.0, 11.0]));
+}
+
 /// A small deterministic generator (xorshift).
 struct Rng(u64);
 impl Rng {