feat(web/ui): unify session opening and add repo card in project list

- Add openSession utility with tab deduplication/focus
- Use openSession in navbar live sessions, use-instance-actions, and project tool links
- Pass onAddRepository to ProjectListItem and add dashed 'Add Repository' card
- Style add-repo card in projects.css

apps/web/src/pages/ProjectsPage.tsx

@@ -252,6 +252,10 @@ export const ProjectsPage = () => {
 							onDelete={() => setDeleteConfirmId(project.id)}
 							onConfirmDelete={() => void handleDelete(project.id)}
 							onCancelDelete={() => setDeleteConfirmId(null)}
+							onAddRepository={() => {
+								setSelectedProject(project);
+								setMobileView("create-repo");
+							}}
 						/>
 					))}
 				</div>