feat: implement project export to Excel with API endpoint and UI button

src/app/projects/page.js

@@ -123,6 +123,28 @@ export default function ProjectListPage() {
 		setSearchTerm('');
 	};
 
+	const handleExportExcel = async () => {
+		try {
+			const response = await fetch('/api/projects/export');
+			if (response.ok) {
+				const blob = await response.blob();
+				const url = window.URL.createObjectURL(blob);
+				const a = document.createElement('a');
+				a.href = url;
+				a.download = `projects_export_${new Date().toISOString().split('T')[0]}.xlsx`;
+				document.body.appendChild(a);
+				a.click();
+				window.URL.revokeObjectURL(url);
+				document.body.removeChild(a);
+			} else {
+				alert('Failed to export projects. Please try again.');
+			}
+		} catch (error) {
+			console.error('Export error:', error);
+			alert('An error occurred during export. Please try again.');
+		}
+	};
+
 	const toggleFilters = () => {
 		setFiltersExpanded(!filtersExpanded);
 	};
@@ -203,6 +225,27 @@ export default function ProjectListPage() {
 							{t('projects.mine') || 'Moje'}
 						</Button>
 					)}
+					<Button 
+						variant="outline" 
+						size="lg" 
+						className="w-full sm:w-auto"
+						onClick={handleExportExcel}
+					>
+						<svg
+							className="w-5 h-5 mr-2"
+							fill="none"
+							stroke="currentColor"
+							viewBox="0 0 24 24"
+						>
+							<path
+								strokeLinecap="round"
+								strokeLinejoin="round"
+								strokeWidth={2}
+								d="M12 10v6m0 0l-3-3m3 3l3-3m2 8H7a2 2 0 01-2-2V5a2 2 0 012-2h5.586a1 1 0 01.707.293l5.414 5.414a1 1 0 01.293.707V19a2 2 0 01-2 2z"
+							/>
+						</svg>
+						{t('projects.exportExcel') || 'Export to Excel'}
+					</Button>
 					<Link href="/projects/new" className="w-full sm:w-auto">
 						<Button variant="primary" size="lg" className="w-full">
 							<svg