feat: improve language switcher integration across all web apps

- Add language selector to PillNavigation in all apps
- Update LanguageSelector components to use shared-i18n utils
- Simplify AppSlider components
- Add getLanguageDropdownItems and getCurrentLanguageLabel utils

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/shared-ui/src/navigation/PillNavigation.svelte

@@ -338,7 +338,6 @@
 					items={languageItems}
 					direction="down"
 					label={currentLanguageLabel}
-					icon="globe"
 				/>
 			{/if}