feat(ST-1133): entityDialogContentClasses → full-screen op <640px (T-316/T-317/T-318)

Eén edit op de gedeelde constant dekt PbiDialog, StoryDialog, TaskDialog,
TaskDetailDialog (allen renderen DialogContent met dezelfde className).

Toegevoegd: max-sm:w-screen max-sm:h-screen max-sm:max-h-screen
max-sm:max-w-none max-sm:rounded-none. Desktop-classes (sm:max-w-[90vw],
lg:max-w-[50vw]) blijven onveranderd.

Tests: smoke op constant + regressie-vangnet dat de 4 entity-dialogen
entityDialogContentClasses blijven gebruiken.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/shared/entity-dialog-layout.ts

@@ -3,6 +3,7 @@ import { cn } from '@/lib/utils'
 export const entityDialogContentClasses = cn(
   'flex flex-col p-0 gap-0',
   'max-h-[90vh] w-full max-w-[calc(100%-2rem)]',
+  'max-sm:w-screen max-sm:h-screen max-sm:max-h-screen max-sm:max-w-none max-sm:rounded-none',
   'sm:max-w-[90vw] sm:max-h-[85vh]',
   'lg:max-w-[50vw] lg:min-w-[480px]',
 )