feat: 音量滑块范围改为 1-5（对应传参 0-4）

tauri-app/src/pages/VideoCreation/VoiceSynthesis.tsx

@@ -522,21 +522,21 @@ export default function VoiceSynthesis() {
           <div className="voice-section">
             <div className="voice-section-header">
               <span className="voice-section-title">音量</span>
-              <span className="speed-value">{volume}</span>
+              <span className="speed-value">{volume + 1}</span>
             </div>
             <div className="speed-slider-wrap">
-              <span>0</span>
+              <span>1</span>
               <input
                 type="range"
                 className="slider-input"
-                min={0}
-                max={10}
+                min={1}
+                max={5}
                 step={1}
-                value={volume}
-                onChange={e => { const v = parseInt(e.target.value); setVolume(v); saveMetaToLocalFile({ voiceVolume: v }); }}
-                style={{ '--slider-percent': `${(volume / 10) * 100}%` } as React.CSSProperties}
+                value={volume + 1}
+                onChange={e => { const v = parseInt(e.target.value) - 1; setVolume(v); saveMetaToLocalFile({ voiceVolume: v }); }}
+                style={{ '--slider-percent': `${((volume) / 4) * 100}%` } as React.CSSProperties}
               />
-              <span>10</span>
+              <span>5</span>
             </div>
           </div>