Frontend: complete task list (C1–L4), security, a11y, L1 block card helper

- React: response.ok checks (address, transaction, search); block number validation; stable Table keys; API modules (addresses, transactions, blocks normalizer)
- SPA: escapeHtml/safe URLs/onclick; getRpcUrl in rpcCall; cancel blocks rAF on view change; named constants; hash route decode
- SPA: createBlockCardHtml + normalizeBlockDisplay (L1); DEBUG console gating; aria-live for errors; token/block/tx detail escaping
- Docs: FRONTEND_REVIEW.md, FRONTEND_TASKS_AND_REVIEW.md; favicons; .gitignore *.tsbuildinfo

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/common/Table.tsx

@@ -11,9 +11,11 @@ interface TableProps<T> {
   columns: Column<T>[]
   data: T[]
   className?: string
+  /** Stable key for each row (e.g. row => row.id or row => row.hash). Falls back to index if not provided. */
+  keyExtractor?: (row: T) => string | number
 }
 
-export function Table<T>({ columns, data, className }: TableProps<T>) {
+export function Table<T>({ columns, data, className, keyExtractor }: TableProps<T>) {
   return (
     <div className={clsx('overflow-x-auto', className)}>
       <table className="min-w-full divide-y divide-gray-200 dark:divide-gray-700">
@@ -34,7 +36,7 @@ export function Table<T>({ columns, data, className }: TableProps<T>) {
         </thead>
         <tbody className="bg-white dark:bg-gray-900 divide-y divide-gray-200 dark:divide-gray-700">
           {data.map((row, rowIndex) => (
-            <tr key={rowIndex} className="hover:bg-gray-50 dark:hover:bg-gray-800">
+            <tr key={keyExtractor ? keyExtractor(row) : rowIndex} className="hover:bg-gray-50 dark:hover:bg-gray-800">
               {columns.map((column, colIndex) => (
                 <td
                   key={colIndex}