Sketch on cut walls, chamfers, pattern copies, join-merged sides and split faces (#625)

A flat face that no construction certificate names on its own now attaches by its exact history name (a new lineage face certificate): cut walls and floors, chamfer faces, each pattern or mirror copy, side walls a Join merged, and the pieces a later feature split a face into. Construction certificates still come first; a seed keeps its certificate when it is patterned. Two flush extrudes of one outline joined end to end keep their exact history in the prism boolean. Face sketch 52% -> 71%, offset plane 52% -> 71%, press-pull/extrude from face 41% -> 60% in the action matrix; baseline blessed.

Fixes #491, fixes #492, fixes #493, fixes #557.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/kernel/src/history.rs

@@ -6,6 +6,14 @@
 //! the operation's own operand list, which each operation documents. A body made by an
 //! operation carries its history (see [`Body::history`]); [`History::substitute`] composes an
 //! operation with one that made one of its operands.
+//!
+//! This is what persistent names and face attachments stand on. The document composes each
+//! feature's histories into face names (`F5:side:l1`, `F7:blend:…`, `F4:top@F6.2`, see
+//! `solidcraft_doc::history_names`); a name is exact only when every operation on the way
+//! reported its history. A flat face with an exact name takes a durable sketch attachment by that
+//! name (`FaceCertificate::Lineage`, docs/face-attachments.md), so an operation that records its
+//! history here gives its faces attachments with no attachment code of its own. An operation
+//! that can't should leave its result without one (`Body::without_history`), never guess.
 
 use std::collections::BTreeSet;