Enable Mac Catalyst on both targets; make the widget intent parameter optional

Supported Destinations now includes Mac (Mac Catalyst) on the app and the
widget extension. Catalyst requires the iPad device family, so both targets
move to TARGETED_DEVICE_FAMILY "1,2".

The first Catalyst build failed on CalendarSelectionIntent: WidgetConfigurationIntent
requires every @Parameter to be optional, and the macOS SDK enforces that where
the iOS one lets a bare array through. selectedCalendars is now optional.

Behaviour is unchanged — the timeline provider already treated an empty
selection as "show all calendars", so nil folds into the same path.

Verified: builds for both Mac Catalyst and iOS Simulator.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CalendarrWidgets/CalendarrTimelineProvider.swift

@@ -38,8 +38,8 @@ struct CalendarrTimelineProvider: AppIntentTimelineProvider {
 
     private func filtered(_ snapshot: WidgetSnapshot?, by config: CalendarSelectionIntent) -> WidgetSnapshot? {
         guard let snapshot else { return nil }
-        let ids = config.selectedCalendars.map { $0.id }
-        guard !ids.isEmpty else { return snapshot }   // empty = show all
+        let ids = (config.selectedCalendars ?? []).map { $0.id }
+        guard !ids.isEmpty else { return snapshot }   // nothing selected = show all
         let keep = Set(ids)
         return WidgetSnapshot(
             writtenAt:          snapshot.writtenAt,