feat: Implement dark mode support across components and UI elements

- Added dark mode styles to TaskStatusDropdown, TaskStatusDropdownDebug, and TaskStatusDropdownSimple components.
- Introduced ThemeProvider and useTheme hook for managing theme state.
- Updated Button, Card, Input, Loading, Navigation, PageContainer, PageHeader, ProjectCalendarWidget, ProjectMap, SearchBar, States, Tooltip, and other UI components to support dark mode.
- Created ThemeToggle component for switching between light and dark modes.
- Enhanced i18n translations for settings related to theme and language preferences.
- Configured Tailwind CSS to support dark mode with class-based toggling.

src/components/ui/ProjectCalendarWidget.js

@@ -277,7 +277,7 @@ export default function ProjectCalendarWidget({
 					</div>
 				</CardHeader>
 				<CardContent>
-					<div className="text-center py-8 text-gray-500">
+					<div className="text-center py-8 text-gray-500 dark:text-gray-400">
 						Brak aktywnych projektów z terminami
 					</div>
 				</CardContent>