On top of the dead-code elimination in the previous commit:
- Add lazy _ensure_plugins_loaded() bootstrap to ChartTypeRegistry so the
registry is populated even without importing app.py (fixes isolated test runs)
- Delegate _RegistryProxy methods to module-level functions so bootstrap runs
- Guard register() against empty chart_type strings
- Add generate_name + resolve_viz_type to ChartTypePlugin Protocol and
BaseChartPlugin; delegate generate_chart_name/_resolve_viz_type in
chart_utils to the plugin registry
- Add _with_context static helper to BaseChartPlugin (shared by all plugins)
- Fix stale 'five methods' → 'eight methods' docstring in plugin.py
- Add TypeVar _C to normalize_column_names so mypy infers correct return type
- Fix broken tests: update _pre_validate_big_number_config → _pre_validate_chart_type,
remove deleted TestNormalizeXYConfig/TestNormalizeTableConfig classes,
update runtime validator tests for removed _validate_format_compatibility /
_validate_cardinality methods, add x is not None narrowing guards
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
