feat: add Edge TTS rate/pitch sliders to voice settings (#629)

Add speed (rate) and pitch controls for Edge TTS provider:
- Frontend: speedToEdgeRate()/hzToEdgePitch() helpers + UI sliders
- Backend: rate/pitch passthrough in OpenaiTtsRequest and controller
- i18n: add edgeRate/edgePitch keys across all 8 languages
- Rate: 0.5x-2.0x slider, Pitch: -20Hz to +20Hz slider

packages/server/src/controllers/hermes/tts.ts

@@ -38,6 +38,8 @@ export async function openaiProxy(ctx: Context) {
     voice?: string
     speed?: number
     model?: string
+    rate?: string
+    pitch?: string
   }
 
   if (!body.input || typeof body.input !== 'string') {
@@ -57,6 +59,8 @@ export async function openaiProxy(ctx: Context) {
     voice: body.voice,
     speed: body.speed,
     model: body.model,
+    rate: body.rate,
+    pitch: body.pitch,
   })
 
   ctx.set('Content-Type', 'audio/mpeg')