Add localization (DE/EN), vertical-scroll month view, context menus, custom colors

- Vertical-scroll month view with multi-day event spans, zig-zag month
  divider, CW number per week, on-demand event loading while scrolling
- Top bar redesign: icon-only view picker on right, month title centered
- Long-press context menus on day cells (month) and hour slots (week/day)
  for "New event", "Open in week view", "Open in day view", "Open in month view"
- Localization system with system/de/en switch covering top bar, view picker,
  settings, menu, profile, server, accounts, event editor, agenda
- Three new color pickers (text/background/line) + today-marker color
  applied in calendar views; current-time line now uses today color
- App icon: removed alpha channel, accent color set to icon green (#20A050)
- TestFlight: ITSAppUsesNonExemptEncryption=NO baked into Info.plist keys

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Calendarr iOS/Models/AppSettings.swift

@@ -13,6 +13,9 @@ struct AppSettings: Codable {
     var language: String = "de"
     var monthDividerColor: String = "#7090c0"
     var monthLabelColor: String = "#7090c0"
+    var textColor: String = "#FFFFFF"
+    var backgroundColor: String = "#000000"
+    var lineColor: String = "#3A3A3C"
 
     enum CodingKeys: String, CodingKey {
         case defaultView = "default_view"
@@ -27,6 +30,9 @@ struct AppSettings: Codable {
         case language
         case monthDividerColor = "month_divider_color"
         case monthLabelColor = "month_label_color"
+        case textColor = "text_color"
+        case backgroundColor = "background_color"
+        case lineColor = "line_color"
     }
 }