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/session/StepRatingModal.tsx

@@ -62,7 +62,7 @@ export function StepRatingModal({
   const handleSubmit = async () => {
     // Filter out steps with no rating
     const ratingsToSubmit = new Map(
-      Array.from(ratings.entries()).filter(([_, data]) => data.rating > 0)
+      Array.from(ratings.entries()).filter(([, data]) => data.rating > 0)
     )
 
     if (ratingsToSubmit.size === 0) {