feat: preserve body history and placed modelling workflows

Record ownership transfers in the timeline so earlier Join/Cut membership,
world placement, machining data and styles survive component moves, edits,
independent copying, undo and reopening. Preserve pending positions in history
snapshots and keep constructor transfers ordered during feature redefinition.

Retain shallow sheet pockets and exact planar intersection islands through
unfold/refold, with depth-aware flat previews and DXF export. Store explicit
3D wire coordinate spaces and migrate known legacy provenance without moving
saved points or analytic fits.

Infer unique eligible cylindrical Emboss targets, align Revolve manipulators
with actual extent geometry, and discard obsolete preview errors after input
correction. Certify constructed and immutable imported face styles using exact
source metadata while preserving legacy face names. Upgrade designs to format10
with bounded validation and geometry-preserving legacy migration.

docs/book/src/guide/files.md

@@ -18,7 +18,11 @@ replaced version is kept as `<file>.bak`. Unsaved changes are autosaved to a rec
 and the next launch offers to recover them. Older design files are upgraded on open, and files
 from a newer version are refused with a message.
 
-Current designs use format 9 for semantic configuration styles, associative free-form offsets
-and explicit cylindrical emboss selections. Older geometry and expressions retain their
-meaning during upgrade; missing new fields use defaults. Association records and occurrence
-paths are bounded and checked before they can alter geometry.
+Current designs use format 10 for recorded body transfers, explicit 3D curve coordinate
+spaces and certified face bindings, alongside semantic configuration styles, associative
+free-form offsets and cylindrical emboss selections. Older ownership maps, geometry and
+expressions retain their saved meaning. Legacy 3D curves with retained associations receive
+their producer's coordinate-space marker without changing any saved points; detached curves
+retain world coordinates. A lost cross-component association refreshed by an older build may
+need an explicit relink or refresh when its source returns. Loading never guesses a numerical
+correction. Association records, coordinate arrays and placements are bounded and checked.