feat(volume): Live-Volume-API + UI-Range setzt Lautstärke während Wiedergabe

web/src/App.tsx

@@ -1,5 +1,5 @@
 import React, { useEffect, useMemo, useState } from 'react';
-import { fetchChannels, fetchSounds, playSound } from './api';
+import { fetchChannels, fetchSounds, playSound, setVolumeLive } from './api';
 import type { VoiceChannelInfo, Sound } from './types';
 
 export default function App() {
@@ -88,7 +88,14 @@ export default function App() {
             max={1}
             step={0.01}
             value={volume}
-            onChange={(e) => setVolume(parseFloat(e.target.value))}
+            onChange={async (e) => {
+              const v = parseFloat(e.target.value);
+              setVolume(v);
+              if (selected) {
+                const [guildId] = selected.split(':');
+                try { await setVolumeLive(guildId, v); } catch {}
+              }
+            }}
             aria-label="Lautstärke"
           />
         </div>

web/src/api.ts

@@ -28,6 +28,18 @@ export async function playSound(soundName: string, guildId: string, channelId: s
   }
 }
 
+export async function setVolumeLive(guildId: string, volume: number): Promise<void> {
+  const res = await fetch(`${API_BASE}/volume`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ guildId, volume })
+  });
+  if (!res.ok) {
+    const data = await res.json().catch(() => ({}));
+    throw new Error(data?.error || 'Volume ändern fehlgeschlagen');
+  }
+}
+