[library / gdsii] cleanup using new library rework

MIGRATION.md

@@ -606,6 +606,17 @@ unchanged until every borrowing view or overlay is finished, then close the
 owning source explicitly. An eager `build(output='library')` result is detached
 and does not need its sources afterward.
 
+Lazy GDS sources no longer provide `with_ports_from_data()` or
+`with_port_overrides()` convenience methods. Construct the generic view
+directly instead: `PortsLibraryView(source, layers=...)` imports port data, and
+`PortsLibraryView(source, ports=..., replace=...)` applies explicit overrides.
+
+Generic borrowing views no longer expose GDS-specific `raw_struct_bytes()`,
+`can_copy_raw_struct()`, or forwarded `library_info` attributes. Keep the
+owning GDS source or the metadata returned by `readfile()` when direct access is
+needed. `IBorrowing.source_cell()` now provides format-neutral per-cell
+provenance; GDS writers use it internally to preserve safe raw copy-through.
+
 Read-only `subtree()` results are now borrowed lazy views rather than eager
 `LibraryView` snapshots. Creating one no longer loads its reachable patterns,
 and the view preserves source ordering, hierarchy metadata, and lazy GDS
@@ -681,8 +692,10 @@ erases the marker.
 libraries and expose them through `borrowed_sources()`. Keep those sources open
 and unchanged for the lifetime of the borrowing view. Owner libraries such as
 `LazyLibrary` and the lazy GDS readers are materializable but do not implement
-`IBorrowing`. GDS raw-structure copy-through remains a separate,
-format-specific capability.
+`IBorrowing`. Borrowing views may expose unchanged per-cell layout provenance
+through `source_cell()`; format writers decide whether that provenance permits
+raw copy-through. Raw GDS structure access remains confined to GDS sources and
+writers.
 
 `LibraryBuilder`, `OverlayLibrary`, and `PortsLibraryView` are new additive
 library implementations. `LibraryBuilder` supports declarative `@cell` recipes