feat(i18n): Implement multilingual support with Polish and English translations

- Added translation context and provider for managing language state.
- Integrated translation functionality into existing components (TaskStatusDropdown, Navigation).
- Created LanguageSwitcher component for language selection.
- Updated task statuses and navigation labels to use translations.
- Added Polish translations for various UI elements, including navigation, tasks, projects, and contracts.
- Refactored utility functions to return localized strings for deadlines and date formatting.

src/app/contracts/page.js

@@ -11,8 +11,10 @@ import SearchBar from "@/components/ui/SearchBar";
 import FilterBar from "@/components/ui/FilterBar";
 import { LoadingState } from "@/components/ui/States";
 import { formatDate } from "@/lib/utils";
+import { useTranslation } from "@/lib/i18n";
 
 export default function ContractsMainPage() {
+	const { t } = useTranslation();
 	const [contracts, setContracts] = useState([]);
 	const [loading, setLoading] = useState(true);
 	const [searchTerm, setSearchTerm] = useState("");
@@ -133,13 +135,13 @@ export default function ContractsMainPage() {
 	const getStatusBadge = (status) => {
 		switch (status) {
 			case "active":
-				return <Badge variant="success">Aktywna</Badge>;
+				return <Badge variant="success">{t('contracts.active')}</Badge>;
 			case "completed":
-				return <Badge variant="secondary">Zakończona</Badge>;
+				return <Badge variant="secondary">{t('common.completed')}</Badge>;
 			case "ongoing":
-				return <Badge variant="primary">W trakcie</Badge>;
+				return <Badge variant="primary">{t('contracts.withoutEndDate')}</Badge>;
 			default:
-				return <Badge>Nieznany</Badge>;
+				return <Badge>{t('common.unknown')}</Badge>;
 		}
 	};
 
@@ -170,17 +172,17 @@ export default function ContractsMainPage() {
 		return (
 			<PageContainer>
 				<PageHeader
-					title="Umowy"
-					description="Zarządzaj swoimi umowami i kontraktami"
+					title={t('contracts.title')}
+					description={t('contracts.subtitle')}
 				>
 					<Link href="/contracts/new">
 						<Button variant="primary" size="lg">
 							<span className="mr-2">➕</span>
-							Nowa umowa
+							{t('contracts.newContract')}
 						</Button>
 					</Link>
 				</PageHeader>
-				<LoadingState message="Ładowanie umów..." />
+				<LoadingState message={t('navigation.loading')} />
 			</PageContainer>
 		);
 	}
@@ -225,13 +227,13 @@ export default function ContractsMainPage() {
 	return (
 		<PageContainer>
 			<PageHeader
-				title="Umowy"
-				description="Zarządzaj swoimi umowami i kontraktami"
+				title={t('contracts.title')}
+				description={t('contracts.subtitle')}
 			>
 				<Link href="/contracts/new">
 					<Button variant="primary" size="lg">
 						<span className="mr-2">➕</span>
-						Nowa umowa
+						{t('contracts.newContract')}
 					</Button>
 				</Link>{" "}
 			</PageHeader>