v2.0.0

This release aligns the package with the front-end data model described in
chapter 4 of the underlying PhD thesis. The user-facing API now consists of
two classes (BuildingInformationModel, GenericElement) plus an
explicit spatial tree, an interaction graph, a Pydantic-based validation
engine, and a parametric geometry layer. Internal helpers have been
reorganised accordingly and the legacy compas_ifc.model entry point is
gone.

Added

• compas_ifc.bim.BuildingInformationModel — the front-end model class,
  combining ElementFactoryMixin, InteractionMixin, and TreeMixin.
• compas_ifc.element.GenericElement — unified element abstraction with
  bidirectional sync to the underlying IFC entity. Replaces per-product
  subclasses for everyday usage.
• compas_ifc.factory.ElementFactoryMixin — typed creators
  (create_wall, create_slab, …) plus a template() classmethod that
  scaffolds default IfcProject / IfcSite / IfcBuilding / IfcBuildingStorey.
• create_element now normalises arbitrary type strings ("IfcWall",
  "Wall", "wall" → IfcWall) and falls back to
  IfcBuildingElementProxy (with ObjectType preserved) for unknown
  custom strings.
• compas_ifc.tree.TreeMixin — IFC import with placement-chain
  rectification, extract/export for self-contained subsets,
  print_hierarchy.
• compas_ifc.interactions.InteractionMixin — typed interaction graph
  populated from IFC relationships, plus compute_connections,
  compute_collisions, and show_collisions.
• compas_ifc.validation — Specification dataclass, validate_model,
  validate_element, and Pydantic schemas for the standard IFC psets.
  Specifications attached to model.specifications enforce validation at
  insertion time; model.validate(specs) runs advisory checks.
• compas_ifc.representations — parametric geometry types (Extrusion,
  Revolution, Pipe, ClippedExtrusion, BooleanResult, HalfSpace)
  that round-trip losslessly through IFC.
• compas_ifc.algorithms.contacts and algorithms.collisions — vectorised
  NumPy + Shapely broadphase + narrowphase replacements for the previous
  pure-Python implementations.
• thesis/appendix/A/ — reproducible evaluation suite for chapter 4 of
  the thesis, with a run_all.py runner that writes a consolidated
  outputs/A-summary.txt.
• tests/test_bim.py and tests/test_validation.py — minimal pytest
  coverage of the front-end API.

Changed

• The package entry point is now
  from compas_ifc.bim import BuildingInformationModel. The previous
  from compas_ifc.model import Model import path has been removed.
• Spatial hierarchy is materialised as model.tree (a COMPAS Tree
  instance) with direct parent / children pointers; non-hierarchical
  IFC relationships go into model.graph.
• Documentation has been rewritten end to end (README.md, docs/index,
  docs/architecture, docs/api/*, docs/tutorials/*,
  docs/examples).

Removed

• compas_ifc.model.Model (replaced by
  compas_ifc.bim.BuildingInformationModel).
• src/compas_ifc/__main__.py (no-op stub).
• tests/test_placeholder.py (replaced by real tests).
• Stale documentation: old tutorial and example pages, the
  compas_ifc.entities.generated API page, the development planning
  notes under thesis/.
• compas_ifc.entities.generated.{IFC2X3,IFC4,IFC4X3} — the runtime
  per-class wrappers (~3,000 files, ~20 MB) have been replaced by three
  PEP 561 stub files (IFC2X3.pyi, IFC4.pyi, IFC4X3.pyi) bundled
  with the package. IDE autocomplete on raw IFC attributes is preserved
  through the stubs; runtime code uses dynamic dispatch through
  Base.__getattr__/__setattr__. Users who relied on
  isinstance(x, IfcWall) should switch to x.is_a("IfcWall");
  runtime imports of compas_ifc.entities.generated.IFC4.IfcWall
  no longer work — type-time imports under if TYPE_CHECKING:
  continue to resolve via the stubs.

Migration notes

• The hand-written extensions in compas_ifc/entities/extensions/
  now register through the new
  :func:compas_ifc.entities.base.extends decorator rather than by
  class name. Each extension class is renamed to Ifc<Name>Extras
  and inherits from Base; the previous class IfcElement(IfcElement)
  shadowing pattern is gone. External code that imported these classes
  by name (e.g. from compas_ifc.entities.extensions import IfcProduct)
  should switch to the new IfcProductExtras name.