feat(FN-1862): add completion state tracking for onboarding

- Add markOnboardingCompleted() to set completedAt timestamp when user finishes onboarding
- Add isOnboardingCompleted() to check if onboarding was completed (vs dismissed)
- Update ModelOnboardingModal to call markOnboardingCompleted on successful completion
- Skip onboarding auto-open when already completed locally
- Add completion state tracking tests in ModelOnboardingModal.test.tsx
- Add model-onboarding-state unit tests
- Update useAuthOnboarding to check local completion state before auto-opening
- Document localStorage completion state tracking pattern in .fusion/memory.md

packages/dashboard/app/hooks/useProjectFileEditor.ts

@@ -63,10 +63,9 @@ export function useProjectFileEditor(
           setOriginalContent(response.content);
           setMtime(response.mtime);
         }
-      } catch (err: unknown) {
+      } catch (err: any) {
         if (!cancelled) {
-          const message = err instanceof Error ? err.message : String(err);
-          setError(message || "Failed to load file");
+          setError(err.message || "Failed to load file");
           setContentState("");
           setOriginalContent("");
           setMtime(null);
@@ -99,9 +98,8 @@ export function useProjectFileEditor(
       const response: SaveFileResponse = await saveWorkspaceFileContent("project", filePath, content);
       setOriginalContent(content);
       setMtime(response.mtime);
-    } catch (err: unknown) {
-      const message = err instanceof Error ? err.message : String(err);
-      setError(message || "Failed to save file");
+    } catch (err: any) {
+      setError(err.message || "Failed to save file");
       throw err;
     } finally {
       setSaving(false);