Add media image handling and related endpoints

- Introduced `MediaImage` entity to manage images for markdown in instructions and news.
- Updated `IAppDbContext` and `AppDbContext` to include `MediaImages` DbSet.
- Implemented `DeleteMediaImageFilesAsync` method in `FactoryResetCommandHandler` to remove media images during factory reset.
- Added new API endpoints for uploading and retrieving media images, enhancing markdown support.
- Updated frontend components to utilize the new `MarkdownEditor` for image uploads in instructions and news.
- Enhanced documentation to reflect the new media handling features and API specifications.

frontend/src/routes/instructions.tsx

@@ -8,11 +8,11 @@ import { useRequireActivated } from '@/features/auth/guards'
 import { AppsCatalog } from '@/features/apps/AppsCatalog'
 import { getInstructionIntro, listInstructionTabs } from '@/features/instructions/api'
 import { cn } from '@/shared/lib/cn'
+import { MARKDOWN_CLASSES } from '@/shared/lib/markdown'
 
 export const Route = createFileRoute('/instructions')({ component: InstructionsPage })
 
 const APPS_TAB_ID = '__apps__'
-const MARKDOWN_CLASSES = '[&_a]:text-primary [&_a]:hover:underline [&_li]:ml-4 [&_ul]:list-disc [&_ol]:list-decimal'
 
 function InstructionsPage() {
   const { t } = useTranslation()