Adds the 1,287 rows the other catalogs have and Italian lacked (filter and adjustment parameters and choices, Camera Raw, Lighting Effects, History and Layers labels, metadata, dialogs), fixes mistranslations in existing rows (Facet, Gradient stops, Save As Preset, Canvas, Spot Color) and uses one term per concept (Predefinito, Traccia, clic, scorciatoia, filmato).
Factors the Korean generated-label check into missing_generated_filter_labels and runs it for Italian too. Adds docs/localization-it.md and updates localization-parity.
