fix(app): replace innerHTML='' with textContent='' in usePlayer

Safer DOM clearing that avoids innerHTML for content sanitization.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/app/src/composables/usePlayer.ts

@@ -106,7 +106,7 @@ export function usePlayer() {
       audioEl.src = result.url
       audioEl.crossOrigin = 'anonymous'
       audioEl.preload = 'auto'
-      containerEl.innerHTML = ''
+      containerEl.textContent = ''
       containerEl.appendChild(audioEl)
       plyrInstance = new Plyr(audioEl, {
         controls: [],
@@ -144,7 +144,7 @@ export function usePlayer() {
       iframe.style.width = '100%'
       iframe.style.height = '100%'
       iframe.style.border = 'none'
-      containerEl.innerHTML = ''
+      containerEl.textContent = ''
       containerEl.appendChild(iframe)
       plyrInstance = null
       audioEl = null
@@ -160,7 +160,7 @@ export function usePlayer() {
     }
     audioEl = null
     if (containerEl) {
-      containerEl.innerHTML = ''
+      containerEl.textContent = ''
     }
   }