``attune_gui.__version__`` was hard-coded to 0.5.0 and stayed there
through the 0.5.1, 0.5.2, 0.5.3, 0.5.4, 0.6.0, 0.6.1, 0.6.2, and
0.7.0 releases. ``app.py`` uses the symbol for the FastAPI app's
OpenAPI metadata, so ``/docs`` and the OpenAPI schema were
advertising a version five releases stale.

Switch to ``importlib.metadata.version("attune-gui")`` so the
symbol tracks ``pyproject.toml`` automatically. Falls back to
``"dev"`` when the package is imported from an uninstalled checkout
(e.g. PYTHONPATH=src without an editable install).

Same pattern attune-help uses today.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>