feat: add task sets functionality with CRUD operations and UI integration

- Implemented NewTaskSetPage for creating task sets with templates.
- Created TaskSetsPage for listing and filtering task sets.
- Enhanced TaskTemplatesPage with navigation to task sets.
- Updated ProjectTaskForm to support task set selection.
- Modified PageHeader to support multiple action buttons.
- Initialized database with task_sets and task_set_templates tables.
- Added queries for task sets including creation, retrieval, and deletion.
- Implemented applyTaskSetToProject function for bulk task creation.
- Added test script for verifying task sets functionality.

src/app/project-tasks/page.js

@@ -10,8 +10,8 @@ export default function ProjectTasksPage() {
 			<PageHeader
 				title="Zadania"
 				description="Zarządzaj zadaniami projektów"
-				action={
-					<Link href="/tasks/templates">
+				actions={[
+					<Link href="/tasks/templates" key="templates">
 						<Button variant="secondary" size="md">
 							<svg
 								className="w-4 h-4 mr-2"
@@ -28,8 +28,26 @@ export default function ProjectTasksPage() {
 							</svg>
 							Szablony zadań
 						</Button>
+					</Link>,
+					<Link href="/task-sets" key="task-sets">
+						<Button variant="secondary" size="md">
+							<svg
+								className="w-4 h-4 mr-2"
+								fill="none"
+								stroke="currentColor"
+								viewBox="0 0 24 24"
+							>
+								<path
+									strokeLinecap="round"
+									strokeLinejoin="round"
+									strokeWidth={2}
+									d="M19 11H5m14 0a2 2 0 012 2v6a2 2 0 01-2 2H5a2 2 0 01-2-2v-6a2 2 0 012-2m14 0V9a2 2 0 00-2-2M5 11V9a2 2 0 012-2m0 0V5a2 2 0 012-2h6a2 2 0 012 2v2M7 7h10"
+								/>
+							</svg>
+							Zestawy zadań
+						</Button>
 					</Link>
-				}
+				]}
 			/>
 			<ProjectTasksList />
 		</PageContainer>