fix(frontend): resolve all eslint errors to zero (B1)

frontend/src/readers/TextReader.tsx

@@ -19,10 +19,17 @@ function useFileText(url: string) {
   const [text, setText] = useState<string | null>(null);
   const [err, setErr] = useState("");
   const [nonce, setNonce] = useState(0);
-  useEffect(() => {
-    let dead = false;
+  // url/nonce 变化时先落回加载态:React 官方推荐的「渲染期按下发 key 重置本地 state」,
+  // 替代原先 effect 内的同步 setState(级联渲染);重试时的表现与原先一致
+  const key = url + "#" + nonce;
+  const [prevKey, setPrevKey] = useState(key);
+  if (prevKey !== key) {
+    setPrevKey(key);
     setText(null);
     setErr("");
+  }
+  useEffect(() => {
+    let dead = false;
     apiRaw(url)
       .then((r) => r.arrayBuffer())
       .then((b) => !dead && setText(decodeText(b)))
@@ -238,6 +245,7 @@ function TxtView({ book, initialLocator, initialPercent, chrome }: ReaderProps)
     const rawCh = Number(initialLocator?.ch);
     if (Number.isFinite(rawCh) && rawCh >= 0 && rawCh < chapters.length) {
       targetCi.current = Math.floor(rawCh);
+      // eslint-disable-next-line react-hooks/set-state-in-effect -- 首章渲染后按缓存 locator 落位阅读进度;ci 与下方滚动定位 effect/refs 协作,改渲染期重置属高风险重构,保守保留
       setCi(Math.floor(rawCh));
       if (hasF) restoreFrac.current = f;
     } else if (hasF) {