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/Assets.xcassets/AccentColor.colorset/Contents.json

@@ -5,9 +5,9 @@
         "color-space" : "srgb",
         "components" : {
           "alpha" : "1.000",
-          "blue" : "0.957",
-          "green" : "0.522",
-          "red" : "0.259"
+          "blue" : "0.314",
+          "green" : "0.627",
+          "red" : "0.125"
         }
       },
       "idiom" : "universal"