### Added
- Turn a calendar off across the whole app. Settings → Calendars now has a
  switch on every calendar — both your own and synced ones. Switching one off
  removes it everywhere: its events disappear from all views and search, and it
  drops out of the drawer's hide/show filter, the event-form calendar picker and
  the import target picker. Unlike hiding (the quick per-view checkbox in the
  drawer), a disabled calendar leaves the app entirely until you turn it back on.
  Nothing is deleted and no other app is affected — it's a Calendula-only view
  choice — so you can re-enable it any time from the same screen, where disabled
  calendars stay listed but dimmed.
- An optional way to support development. Settings → About now has a "Support
  development" button that opens Ko-fi in your browser. It's a plain donation
  link with no perks attached, and it needs no new permissions — Calendula still
  has no internet access of its own and just hands the link to your browser.
