- send a calendar's colour only when the user changed it: Stalwart 1.0
accepts only #rgb, #rrggbb or a CSS name, so renaming a calendar that
another client coloured with an 8-digit hex (Apple Calendar) failed
- "Refresh cached data" kept nothing of the calendar store's persisted
state, so it deleted the user's iCal subscriptions, which exist only
there; keep them and drop the rest
- show a notice with a retry when the task list fails to load; it keeps
the tasks it had
- treat a method-level error on creating a task as a failure with its
JMAP type instead of "no id returned"