fix: archive project navigates to dashboard and shows toast

Previously archiving a project silently navigated to /projects with no
feedback. Now it navigates to /dashboard and shows a success toast for
both archive and unarchive actions.

Closes PAP-521

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

ui/src/pages/ProjectDetail.tsx

@@ -10,6 +10,7 @@ import { heartbeatsApi } from "../api/heartbeats";
 import { assetsApi } from "../api/assets";
 import { usePanel } from "../context/PanelContext";
 import { useCompany } from "../context/CompanyContext";
+import { useToast } from "../context/ToastContext";
 import { useBreadcrumbs } from "../context/BreadcrumbContext";
 import { queryKeys } from "../lib/queryKeys";
 import { ProjectProperties, type ProjectConfigFieldKey, type ProjectFieldSaveState } from "../components/ProjectProperties";
@@ -210,6 +211,7 @@ export function ProjectDetail() {
   const { companies, selectedCompanyId, setSelectedCompanyId } = useCompany();
   const { closePanel } = usePanel();
   const { setBreadcrumbs } = useBreadcrumbs();
+  const { pushToast } = useToast();
   const queryClient = useQueryClient();
   const navigate = useNavigate();
   const location = useLocation();
@@ -284,10 +286,14 @@ export function ProjectDetail() {
         { archivedAt: archived ? new Date().toISOString() : null },
         resolvedCompanyId ?? lookupCompanyId,
       ),
-    onSuccess: (_, archived) => {
+    onSuccess: (updatedProject, archived) => {
       invalidateProject();
+      const name = updatedProject?.name ?? project?.name ?? "Project";
       if (archived) {
-        navigate("/projects");
+        pushToast({ title: `"${name}" has been archived`, tone: "success" });
+        navigate("/dashboard");
+      } else {
+        pushToast({ title: `"${name}" has been unarchived`, tone: "success" });
       }
     },
   });