v0.65.20

Added

• Calendar events are now coloured by their assignee's avatar colour. When a single user is assigned the event background uses their avatar colour; when multiple users are assigned a diagonal CSS gradient (135 °) blends all their colours in equal segments. Events without assignees continue to use the manually set event colour, the calendar's colour, or a neutral grey fallback.
• The event colour picker is visually disabled (greyed out with a hint text) while an assignee is set, reflecting that the assignee colour takes priority. Removing all assignees re-enables the picker.
• Added colorOverriddenByAssignee i18n key to all 18 supported locales.