fix: calendar — register createForm via getForms() + remove broken FullCalendar CSS link

- Filament v5 multi-form pages need protected getForms() returning form names
- FullCalendar v6 bundles CSS in JS — separate <link> 404'd silently
- Added Russian locale alongside Romanian for i18n switcher

app/Filament/Tenant/Pages/CalendarBoard.php

@@ -34,6 +34,12 @@ class CalendarBoard extends Page
 
     public ?int $editId = null;
 
+    /** Register all forms used by this page (Filament v5 multi-form pattern). */
+    protected function getForms(): array
+    {
+        return ['createForm'];
+    }
+
     public function getEvents(string $start, string $end): array
     {
         return Appointment::with(['client:id,name', 'vehicle:id,plate,make,model', 'master:id,name,color', 'post:id,name,color'])