fix(presenter): replace crypto.subtle with simple hash for HTTP compatibility

crypto.subtle requires HTTPS context. Use simple string hash instead.

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

pitch-deck/lib/hooks/usePresenterMode.ts

@@ -31,14 +31,17 @@ interface UsePresenterModeReturn {
   setTtsEnabled: (enabled: boolean) => void
 }
 
-// Client-side audio cache: text hash → blob URL
+// Client-side audio cache: text key → blob URL
 const audioCache = new Map<string, string>()
 
-async function hashText(text: string): Promise<string> {
-  const encoder = new TextEncoder()
-  const data = encoder.encode(text)
-  const hash = await crypto.subtle.digest('SHA-256', data)
-  return Array.from(new Uint8Array(hash)).slice(0, 8).map(b => b.toString(16).padStart(2, '0')).join('')
+function cacheKey(text: string, lang: string): string {
+  // Simple string hash — no crypto.subtle needed (works on HTTP too)
+  let hash = 0
+  const str = text + '|' + lang
+  for (let i = 0; i < str.length; i++) {
+    hash = ((hash << 5) - hash + str.charCodeAt(i)) | 0
+  }
+  return 'tts_' + (hash >>> 0).toString(36)
 }
 
 export function usePresenterMode({
@@ -162,7 +165,7 @@ export function usePresenterMode({
 
       const playAudio = async () => {
         try {
-          const key = await hashText(text + language)
+          const key = cacheKey(text, language)
           let blobUrl = audioCache.get(key)
 
           if (!blobUrl) {