Add archive project button and filter archived projects from selectors

- Add "Archive project" / "Unarchive project" button in the project
  configuration danger zone (ProjectProperties)
- Filter archived projects from the Projects listing page
- Filter archived projects from NewIssueDialog project selector
- Filter archived projects from IssueProperties project picker
  (keeps current project visible even if archived)
- Filter archived projects from CommandPalette
- SidebarProjects already filters archived projects

Co-Authored-By: Paperclip <noreply@paperclip.ing>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/components/CommandPalette.tsx

@@ -75,11 +75,15 @@ export function CommandPalette() {
     enabled: !!selectedCompanyId && open,
   });
 
-  const { data: projects = [] } = useQuery({
+  const { data: allProjects = [] } = useQuery({
     queryKey: queryKeys.projects.list(selectedCompanyId!),
     queryFn: () => projectsApi.list(selectedCompanyId!),
     enabled: !!selectedCompanyId && open,
   });
+  const projects = useMemo(
+    () => allProjects.filter((p) => !p.archivedAt),
+    [allProjects],
+  );
 
   function go(path: string) {
     setOpen(false);