fix: resolve all 15 frontend ESLint errors for green CI

- Replace setState-in-effect with state-based tracking (AdminLayout, EditCategoryModal)
- Convert inline SortIcon component to getSortIcon function (TreeTableView)
- Remove unused catch parameters (CreateCategoryModal, EditCategoryModal)
- Replace `any` types with proper types (SessionFilters, AdminCategoriesPage, SessionHistoryPage)
- Fix unused destructuring variable (StepRatingModal)
- Fix constant binary expression in test (utils.test.ts)

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

frontend/src/components/admin/CreateCategoryModal.tsx

@@ -43,7 +43,7 @@ export function CreateCategoryModal({
       // Reset form on success
       setName('')
       setDescription('')
-    } catch (err) {
+    } catch {
       setError('Failed to create category')
     }
   }