fix(maps): let users and admins enter a CARTO API key (#2060)

CARTO stamps an "API KEY REQUIRED" watermark onto every basemap tile
fetched without a key since 26.08.2026, and both CartoDB presets plus the
built-in fallback are CARTO. The key is free and needs no account, so add
it as a setting rather than dropping the provider.

carto_api_key sits next to mapbox_access_token: per user in Settings/Map,
instance-wide under Admin/User Defaults, encrypted at rest, injected from
CARTO_API_KEY on managed instances. Unlike Mapbox it never switches the
map provider, since a raster key says nothing about the renderer.

The key is appended as ?key= at render time instead of being stored in the
template, so a saved URL stays portable and survives a rotation. That is
also what reaches the four maps that pinned CARTO and ignored the user's
tile setting: atlas, collections, the public trip share and the public
journey. The two share pages read it from their token-gated payload, the
same way baseCurrency already travels.

Also lifts the release notice above page chrome. Its overlay sat at
z-index 50, under the Vacay mode toolbar at 61, so the dialog was neither
on top nor modal. Adds a six-step layer scale to index.css and moves the
three notice shells onto it.

Closes #2054
Closes #2052

shared/src/i18n/pl/admin.ts

@@ -702,6 +702,9 @@ const admin: TranslationStrings = {
   'admin.defaultSettings.mapboxStylePlaceholder': 'Wybierz styl…',
   'admin.defaultSettings.mapbox3d': 'Budynki i teren 3D',
   'admin.defaultSettings.mapboxQuality': 'Tryb wysokiej jakości',
+  'admin.defaultSettings.cartoKey': 'Współdzielony klucz CARTO',
+  'admin.defaultSettings.cartoKeyHint':
+    'Używany dla każdego użytkownika, który nie wprowadził własnego klucza, dzięki czemu cała instancja otrzymuje kafelki CARTO bez znaku wodnego. Przechowywany w postaci zaszyfrowanej.',
   'admin.group.users': 'Users',
   'admin.group.config': 'Configuration',
   'admin.group.integration': 'Integrations',