Adapt codegen for new parsing

Fix: commit pending parametric draft before extrusion-edit

EnableEditingExtrusionAxis and EnableEditingExtrusionProfile both
import a mesh from the IFC representation into obj.data as their
first real action. That mesh-import overwrites any in-memory
parametric (gizmo) draft on the object, silently discarding the
user's pending dimension edits.

Concrete reproduction: drag a wall's length gizmo (draft pending),
then click "Edit Axis" before validating the draft. The axis-edit
imports the wall axis mesh; the in-flight draft vanishes; on
cancel the wall snaps back to its pre-drag length.

Both call sites now commit the active draft via
tool.Parametric.commit_object_draft before the mesh import, gated
on tool.Parametric.is_object_editing so the guard is a no-op when
no draft is in flight.

Generated with the assistance of an AI coding tool.

Refactor: rename rel -> subject in disconnect_rel dispatch

The "mep-pair-fitting" kind added in the previous commit carries an
IfcFlowFitting (the entity whose deletion disconnects the pair), not a
relationship entity, in the dispatch slot — but the slot was named ``rel``
across the function signature and every call site. Rename to ``subject``
so the parameter name reflects the uniform intent: "the entity whose
teardown effects the disconnect", regardless of whether that's a rel or
a fitting.

Sweep covers:

- core.connection.disconnect_rel signature + body
- tool.Connection.find_rels / find_rels_for_element / find_rel docstrings
- The cascade-on-delete call site in tool.Geometry.delete_ifc_object
- DisconnectElements operator in bim.module.model.wall
- All affected test kwargs and AST forward-compat docstring
- Error message: "Unknown rel kind" -> "Unknown kind"

No behaviour change.

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Merge pull request #8195 from Gorgious56/bonsai/ifc-migrate-ifc2x3-do…

…wngrade

Bonsai/ifc migrate ifc2x3 downgrade + patch preset system

Clip box: include linked IFC geometry

Add include_linked_ifc toggle on BIMSceneClipBoxProperties so the cap
pipeline can also bisect meshes inside Project > Links collection-instance
empties. Off by default - linked IFCs may carry the entire site or
structural backbone, and capping them adds per-mesh bisect cost on every
clip-box edit.

The new iterator composes instance.matrix_world @ inner.matrix_world as
the effective world placement so caps land in the active scene rather
than at the linked library's local origin. Linked-mesh cache entries are
namespaced with a 'link:' prefix to avoid collisions with top-level
scene objects.

Generated with the assistance of an AI coding tool.

Apply black formatting and ruff isort fixes

Pre-commit checklist: black + ruff check.

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Add network path overlay for walls and MEP

Adds a viewport overlay that traces the connected element path from
the selected wall or MEP element. Walls follow IfcRelConnectsPathElements
and draw each connected wall's reference axis with endpoint dots; MEP
elements follow IfcRelConnectsPorts and draw each segment's axis plus
a port-to-port spider for each fitting.

The new BIMModelProperties.show_paths toggle (Element Paths in the
Bonsai Decorators group of Blender's viewport overlay popover) drives
install / uninstall of both decorators on flip and on file load,
mirroring the show_slab_direction wiring. The popover row also
surfaces the pre-existing BIMSystemProperties.should_draw_decorations
toggle (System Decorations) so both connectivity overlays sit
together.

Dot colors split free endpoints (decorator_color_special, blue by
default) from junction nodes (decorator_color_selected, green by
default) so dangling chain tips read apart from interior joins. Walls
classify endpoints by IFC topology: rels expose RelatingConnectionType /
RelatedConnectionType and ATPATH dots use tool.Wall.path_connection_location_world
for the canonical T-meets join. MEP keeps the geometric classifier
because port positions coincide exactly across fitting + segment.

Generated with the assistance of an AI coding tool.

Fix clip-box edit-mode picker + rotation margin

Edit-mode click-select rejected verts inside the clip volume
because clip_bb stayed at the first-arm view; the depsgraph and
PRE_VIEW handlers updated clip_planes but skipped the
view3d.clip_border call that refreshes clip_bb. Schedule a full
re-arm at transform-commit, IFC reload, and view drift.

The empty's wireframe was clipped by its own planes when rotated
at non-trivial scale because the 1e-6 absolute margin can't
absorb float-precision drift that scales with the box's world
half-extent. Add a 1e-5 relative expand.

Generated with the assistance of an AI coding tool.

Fix clip-box edit-mode picker + rotation margin

Edit-mode click-select rejected verts inside the clip volume
because clip_bb stayed at the first-arm view; the depsgraph and
PRE_VIEW handlers updated clip_planes but skipped the
view3d.clip_border call that refreshes clip_bb. Schedule a full
re-arm at transform-commit, IFC reload, and view drift.

The empty's wireframe was clipped by its own planes when rotated
at non-trivial scale because the 1e-6 absolute margin can't
absorb float-precision drift that scales with the box's world
half-extent. Add a 1e-5 relative expand.

Generated with the assistance of an AI coding tool.

Fix loading project library without IfcProject

Per IFC4+, IfcContext is the abstract supertype of IfcProject and
IfcProjectLibrary; library-only files legitimately contain only
IfcProjectLibrary as their root context. Bonsai assumed an IfcProject
was always present at three crash sites: the parent-library enum
(reported in #8183), RefreshLibrary's tree view, and AddProjectLibrary.

Introduce tool.Project.get_root_context() that prefers IfcProject and
falls back to IfcProjectLibrary, and route the three sites through it.
get_parent_library() now returns None for a root IfcProjectLibrary;
get_project_hierarchy() and the EditProjectLibrary parent-swap branch
handle that. AddProjectLibrary creates the nested sub-library via
IfcRelNests when the root is an IfcProjectLibrary, matching the
existing convention for library-under-library nesting.

For the separate "Open IFC Project" path, abort with a friendly error
pointing users to Project Setup -> Project Library -> Select Library
File instead of letting set_units() crash deep in the importer.

Closes #8183.

Partly generated with the assistance of an AI coding tool.