A11y: Localize aria-label in DocRoleDropdown

[rvveber]

docs/src/frontend/apps/impress/src/features/docs/doc-share/components/DocRoleDropdown.tsx

Lines 113 to 116 in a4e3168

	return (
	<DropdownMenu
	topMessage={topMessage}
	label="doc-role-dropdown"

• Problem: The dropdown trigger hardcodes aria-label="doc-role-dropdown", so assistive tech literally announces the English slug instead of a descriptive, localized label.
• Impact: Non-descriptive labels make it impossible for users to understand the control’s purpose, especially in translated interfaces.
• Acceptance criteria / fix ideas:
  • Replace the hardcoded string with a translated phrase (e.g., t('Document role options')).
  • Ensure the label matches the control’s function and is localized alongside the rest of the UI.