feat(kernel): an edge's meeting sides are sets of origins (merged faces)

EdgeOrigin::Meet now names each side as a Side: the sorted, de-duplicated
origins of the face there. substitute maps a side to the union of the inner
faces' origins, so a meeting with a face an inner operation merged keeps its
lineage; meeting() derives sides from whole faces. Fillets after box cuts
that leave coplanar pieces now report exact history. Prism lineage meets a
cap of several origins and resolves wall junctions away from shared
vertices by the operand's one edge between the walls. bore_union's recut
reports history only for a one-face bore (pieces of a two-arc bore's recut
wall were given both arcs).

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

crates/kernel/src/boolean_record.rs

@@ -112,7 +112,7 @@ pub(crate) fn shapeops(h: &truck_shapeops::History, tool: &Solid, tool_edges: Op
                 tool_edges.and_then(|t| t.get(passed.get(edge)?)).cloned()
             }
             truck_shapeops::EdgeOrigin::Edge { operand, edge } => Some(vec![EdgeOrigin::Edge { operand, edge }]),
-            truck_shapeops::EdgeOrigin::Meet { a, b } => Some(vec![EdgeOrigin::Meet { a: face(a), b: face(b) }]),
+            truck_shapeops::EdgeOrigin::Meet { a, b } => Some(vec![EdgeOrigin::meet(face(a), face(b))]),
         })
         .collect::<Option<Vec<_>>>()?;
     Some((faces, edges))