Version 7.8.1
=============

Patch release: makes **project-exported BUML files load again in the
Web Modeling Editor**. v7.8.0's project import flow rejected
``model.py`` files that embed a ``Project(...)`` wrapper around a flat
domain-model block, returning a "Could not parse BUML file" error or,
worse, silently importing an empty diagram. No metamodel, generator,
or API contract changes — backend-only.

Fixes
-----

* **``parse_buml_content`` sandbox missing ``Project``**: the class
  diagram converter's ``exec()`` sandbox in
  ``besser/utilities/web_modeling_editor/backend/services/converters/buml_to_json/class_diagram_converter.py``
  strips ``import`` and ``from`` statements before execution and
  injects the metamodel symbols it needs. ``Project`` was never in
  that injection list, so any file whose tail looked like
  ``project = Project(name=..., models=[domain_model], ...)`` failed
  with ``NameError: name 'Project' is not defined`` before the
  ``DomainModel`` could be lifted out. A no-op ``Project`` stub is
  now provided in the sandbox so trailing project definitions parse
  harmlessly.
* **``project_to_json`` ignored flat project files**: the project
  converter at
  ``besser/utilities/web_modeling_editor/backend/services/converters/buml_to_json/project_converter.py``
  only scans for ``# STRUCTURAL MODEL #`` (and the numbered/titled
  variants) as section anchors. Files exported with the older flat
  layout (``# Classes``, ``# Relationships``, ``# Generalizations``,
  ``# Domain Model``, then ``# PROJECT DEFINITION #``) hit
  ``models=[...]`` but produced zero extracted sections, leaving
  every diagram empty. When section extraction yields nothing,
  ``project_to_json`` now falls back to
  ``_build_project_from_single_diagram`` against the full content
  and restores the project ``name``, ``description``, and ``owner``
  from the ``Project(...)`` wrapper.
* **``/get-json-model`` read the wrong project shape**: the project
  branch in
  ``besser/utilities/web_modeling_editor/backend/routers/conversion_router.py``
  still looked for the legacy flat shape
  (``parsed_project["ClassDiagram"]``) instead of the
  ``schemaVersion=3`` nested shape
  (``parsed_project["diagrams"]["ClassDiagram"][i]``). Even after
  ``project_to_json`` started returning populated diagrams, the
  endpoint surfaced ``None`` and raised "Could not parse BUML file."
  The branch now honours ``currentDiagramType`` and
  ``currentDiagramIndices``, falling through the legacy priority
  order if the active diagram is empty.

A regression test
(``test_project_to_json_handles_missing_section_headers``) in
``tests/utilities/web_modeling_editor/backend/services/converters/test_project_single_diagram_fallback.py``
guards the section-header-less project case end-to-end.