feat(device): 增加耳机最大音量限制及显示提示

- 新增 getHomeVolumeMax 函数，计算耳机输出的最大允许音量
- 新增 getHeadphoneMaxVolumeDb 函数，获取耳机最大音量的 dB 值用于提示显示
- 修改 setVolume 函数，限制音量在动态最大值范围内，防止首页入口发送超限音量
- Home 页面音量滑块、旋钮角度及音量范围由固定 200 调整为当前设备最大音量
- 添加耳机最大音量提示文本，根据用户设置动态显示最大 dB 值
- 各语言文件新增耳机最大音量提示相关文案
- 优化实现，防止拖动时音量显示超出最大音量限制

client/src/pages/Home.tsx

@@ -24,6 +24,8 @@ import {
   AlertDialogTitle,
 } from "@/components/ui/alert-dialog";
 import {
+  getHeadphoneMaxVolumeDb,
+  getHomeVolumeMax,
   INPUT_BLUETOOTH_INDEX,
   INPUT_LABELS,
   isHomeVolumeLockedByPassthrough,
@@ -253,7 +255,10 @@ export default function Home() {
     return null;
   }, [volumeConfirm, homeText]);
 
-  const [localVol, setLocalVol] = useState(deviceState?.volume ?? 100);
+  const maxVolume = getHomeVolumeMax(deviceState);
+  const [volumeDraft, setLocalVol] = useState(deviceState?.volume ?? 100);
+  // 上限或输出切换时立即约束显示，拖动中也不能保留超限值。
+  const localVol = Math.max(0, Math.min(maxVolume, volumeDraft));
   const isDragging = useRef(false);
   const knobDraggingRef = useRef(false);
   const knobActivePointerIdRef = useRef<number | null>(null);
@@ -262,10 +267,10 @@ export default function Home() {
   const knobLastVolRef = useRef<number>(localVol);
 
   useEffect(() => {
-    if (!isDragging.current && deviceState?.volume !== undefined) {
-      setLocalVol(deviceState.volume);
-    }
-  }, [deviceState?.volume]);
+    setLocalVol(current => Math.max(0, Math.min(maxVolume,
+      !isDragging.current && deviceState?.volume !== undefined ? deviceState.volume : current,
+    )));
+  }, [deviceState?.volume, maxVolume]);
 
   useEffect(() => {
     knobLastVolRef.current = localVol;
@@ -456,16 +461,25 @@ export default function Home() {
   const vuLabel = `${homeText.vu ?? "VU表"}${(ds.vu ?? 0) + 1}`;
   const bypassOn = (ds.dsp_enable ?? 0) === 0;
 
+  // 耳机输出且已设置耳机最大音量时，提示当前上限，避免用户误以为还能加到 0dB。
+  const hpMaxVolumeDb = getHeadphoneMaxVolumeDb(ds);
+  const hpMaxVolumeHint =
+    hpMaxVolumeDb === null
+      ? null
+      : (homeText.hpMaxVolumeHint ?? "已设置耳机最大音量，最大音量为：{db}dB").replace(
+          "{db}",
+          String(hpMaxVolumeDb),
+        );
+
   // Home 的 volume 取值为 0..200，对应 dB = (v - 200) / 2
   // 因此 1 个 volume 单位 = 0.5dB
   // AudioPage 的 soundStep：0->0.5dB, 1->1dB, 2->2dB, 3->3dB
   // 换算为 volume 单位：0.5/1/2/3 dB -> 1/2/4/6
   const fineVolumeStep = [1, 2, 4, 6][ds.soundStep ?? 1] ?? 1;
 
-  // Slider fill % (0-200 → 0-100%)
-  const fillPct = (localVol / 200) * 100;
-  // Knob angle (map 0..200 -> -135..+135 degrees)
-  const knobAngle = -135 + (localVol / 200) * 270;
+  // 滑条填充和旋钮角度均按当前输出的最大音量映射。
+  const fillPct = (localVol / maxVolume) * 100;
+  const knobAngle = -135 + (localVol / maxVolume) * 270;
 
   const pointAngle = (clientX: number, clientY: number, rect: DOMRect) => {
     const cx = rect.left + rect.width / 2;
@@ -500,9 +514,9 @@ export default function Home() {
     const rect = el.getBoundingClientRect();
     const a = pointAngle(e.clientX, e.clientY, rect);
     const delta = normalizeDelta(a - knobStartAngleRef.current);
-    // 270deg travel -> full scale; 1 rad maps to ~200/(1.5*pi) volume steps
-    const stepsPerRad = 200 / (Math.PI * 1.5);
-    const next = Math.max(0, Math.min(200, Math.round(knobStartVolRef.current + delta * stepsPerRad)));
+    // 270 度行程对应当前允许的完整音量范围。
+    const stepsPerRad = maxVolume / (Math.PI * 1.5);
+    const next = Math.max(0, Math.min(maxVolume, Math.round(knobStartVolRef.current + delta * stepsPerRad)));
     setLocalVol(next);
     knobLastVolRef.current = next;
   };
@@ -691,7 +705,7 @@ export default function Home() {
               }} />
             <ThumbOnlyRangeSlider
               min={0}
-              max={200}
+              max={maxVolume}
               value={localVol}
               disabled={volumePassthroughActive}
               className={volumePassthroughActive ? "opacity-50" : undefined}
@@ -748,7 +762,7 @@ export default function Home() {
             }}
             onClick={() => {
               if (blockVolumeAdjust()) return;
-              const next = Math.max(0, Math.min(200, localVol - fineVolumeStep));
+              const next = Math.max(0, Math.min(maxVolume, localVol - fineVolumeStep));
               setLocalVol(next);
               applyVolume(next);
             }}
@@ -771,7 +785,7 @@ export default function Home() {
           <button
             type="button"
             aria-label="Increase volume"
-            disabled={volumePassthroughActive || localVol >= 200}
+            disabled={volumePassthroughActive || localVol >= maxVolume}
             className="w-10 h-10 rounded-full flex items-center justify-center transition-all active:scale-95 disabled:opacity-30 disabled:cursor-not-allowed"
             style={{
               background: "rgba(44,44,46,0.6)",
@@ -780,7 +794,7 @@ export default function Home() {
             }}
             onClick={() => {
               if (blockVolumeAdjust()) return;
-              const next = Math.max(0, Math.min(200, localVol + fineVolumeStep));
+              const next = Math.max(0, Math.min(maxVolume, localVol + fineVolumeStep));
               setLocalVol(next);
               applyVolume(next);
             }}
@@ -791,6 +805,16 @@ export default function Home() {
           </button>
         </div>
 
+        {hpMaxVolumeHint && (
+          <p
+            className="mt-2 text-center text-[12px] leading-relaxed"
+            style={{ color: "rgba(255,255,255,0.5)" }}
+            role="status"
+          >
+            {hpMaxVolumeHint}
+          </p>
+        )}
+
         {/* Bluetooth info — only when input source is Bluetooth */}
         {ds.input === INPUT_BLUETOOTH_INDEX && ds.bt_status !== 0 && (
           <div className="mt-3 px-3 py-3 text-center">
@@ -961,8 +985,8 @@ export default function Home() {
                   setLocalVol(0);
                   applyVolume(0);
                 } else if (volumeConfirm === "max") {
-                  setLocalVol(200);
-                  applyVolume(200);
+                  setLocalVol(maxVolume);
+                  applyVolume(maxVolume);
                 }
                 setVolumeConfirm(null);
               }}