`CalendarCubit` follows the projects' calendar links: a calendar linked
is shown at once from the copy kept and fetched by the device over HTTPS
(`HttpCalendarFeeds`, `webcal://` as HTTPS), as the app opens, every hour
while it is open and when a list is pulled down; a fetch that fails, or
answers with something that is no calendar, keeps the last copy; a link
taken off, or its project gone, takes its events and its copy along. The
copies are files in the person's own folder (`calendars/<project>.ics`).
Nothing shows the events yet.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>