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/EditCategoryModal.tsx

@@ -1,4 +1,4 @@
-import { useState, useEffect } from 'react'
+import { useState } from 'react'
 import { X } from 'lucide-react'
 import { cn } from '@/lib/utils'
 import type { StepCategoryListItem } from '@/types'
@@ -21,14 +21,17 @@ export function EditCategoryModal({
   const [name, setName] = useState('')
   const [description, setDescription] = useState('')
   const [error, setError] = useState('')
+  const [prevCategoryId, setPrevCategoryId] = useState<string | null>(null)
 
-  // Pre-populate form when category changes
-  useEffect(() => {
-    if (category) {
-      setName(category.name)
-      setDescription(category.description || '')
-    }
-  }, [category])
+  // Pre-populate form when category changes (state-based tracking)
+  if (category && category.id !== prevCategoryId) {
+    setPrevCategoryId(category.id)
+    setName(category.name)
+    setDescription(category.description || '')
+  }
+  if (!category && prevCategoryId !== null) {
+    setPrevCategoryId(null)
+  }
 
   if (!isOpen || !category) return null
 
@@ -51,7 +54,7 @@ export function EditCategoryModal({
         name: name.trim(),
         description: description.trim()
       })
-    } catch (err) {
+    } catch {
       setError('Failed to update category')
     }
   }