refactor(eq): 更新EQ页面以优化预设缓存和滤波器管理

- 添加实时滑块预览状态以改善用户体验
- 重构预设缓存逻辑，使用新的PeqPresetLocalCache类型管理滤波器和增益设置
- 更新相关函数以支持新的预设缓存机制，减少重复计算
- 增强滤波器持久化逻辑，确保在耳机切换时正确保存和应用滤波器设置

client/src/pages/eq/constants.ts

@@ -52,6 +52,13 @@ export const DEFAULT_BANDS = [
 /* ── PEQ catalog item type ── */
 export type PeqCatalogItem = NonNullable<PeqState["peq"]>[number];
 
+/** 本地编辑缓存（按预设名称）；syncPeq 拉取时优先于设备 catalog */
+export type PeqPresetLocalCache = {
+  filters?: PeqFilter[];
+  preamp?: number;
+  autoPre?: number;
+};
+
 /* ── Flat preset filters ── */
 export const FLAT_PRESET_FILTERS: PeqFilter[] = [
   { type: 4, fc: 80, gain: 0, q: 0.1 },

client/src/pages/eq/utils.ts

@@ -31,6 +31,18 @@ export function formatBandFreqDisplay(freq: number) {
     : `${freq} Hz`;
 }
 
+export function formatBandGainDisplay(gain: unknown) {
+  const db = typeof gain === "number" && Number.isFinite(gain) ? gain : Number(gain);
+  if (!Number.isFinite(db)) return "0.0 dB";
+  const text = db.toFixed(1);
+  return `${db >= 0 ? `+${text}` : text} dB`;
+}
+
+export function formatBandQDisplay(q: unknown) {
+  const n = typeof q === "number" && Number.isFinite(q) ? q : Number(q);
+  return Number.isFinite(n) ? n.toFixed(2) : "—";
+}
+
 /* ── Band param value for input field ── */
 export function formatBandParamForInput(
   kind: BandParamKind,
@@ -131,9 +143,19 @@ export function cloneBands(
   return source.map((band) => ({ ...band }));
 }
 
-/* ── Frequency label for band grid ── */
-export function freqLabel(f: number) {
-  return f >= 1000 ? `${(f / 1000).toFixed(1)}K` : `${f}`;
+/* ── Frequency label for band grid (numeric only; avoid browser translate → words) ── */
+export function freqLabel(freq: unknown) {
+  const hz =
+    typeof freq === "number" && Number.isFinite(freq)
+      ? freq
+      : Number(freq);
+  if (!Number.isFinite(hz)) return "—";
+  if (hz >= 1000) {
+    const k = hz / 1000;
+    const text = k >= 10 ? String(Math.round(k)) : k.toFixed(1).replace(/\.0$/, "");
+    return `${text}K`;
+  }
+  return String(Math.round(hz));
 }
 
 /* ── Build PEQ catalog sync key ── */