fix(lint): resolve remaining ESLint errors (unused vars, any types, react-refresh)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/config/DiffViewer.tsx

@@ -48,8 +48,8 @@ export function DiffViewer({ tenantId, deviceId, snapshotId, onClose }: DiffView
       {/* Content */}
       {isLoading ? (
         <div className="space-y-2">
-          {Array.from({ length: 6 }).map((_, i) => (
-            <div key={i} className="h-4 bg-elevated rounded animate-pulse" style={{ width: `${60 + Math.random() * 40}%` }} />
+          {[75, 90, 65, 85, 70, 80].map((w, i) => (
+            <div key={i} className="h-4 bg-elevated rounded animate-pulse" style={{ width: `${w}%` }} />
           ))}
         </div>
       ) : isError || !diff ? (