Add voice memos to live journal and event log.

Record short E2E-encrypted audio attachments from the live log, link them to events via __live:voice markers, and play them back in the stream and chronological event table.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/utils/audioBlob.ts

@@ -0,0 +1,39 @@
+export const VOICE_MEMO_MAX_DURATION_SEC = 60
+export const VOICE_MEMO_MAX_BLOB_BYTES = 800_000
+
+const MIME_CANDIDATES = [
+  'audio/webm;codecs=opus',
+  'audio/webm',
+  'audio/mp4',
+  'audio/ogg;codecs=opus'
+]
+
+export function pickMediaRecorderMimeType(): string | undefined {
+  if (typeof MediaRecorder === 'undefined') return undefined
+  for (const mime of MIME_CANDIDATES) {
+    if (MediaRecorder.isTypeSupported(mime)) return mime
+  }
+  return undefined
+}
+
+export function blobToAudioDataUrl(blob: Blob): Promise<string> {
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader()
+    reader.onload = () => resolve(String(reader.result))
+    reader.onerror = () => reject(new Error('audio_read_failed'))
+    reader.readAsDataURL(blob)
+  })
+}
+
+export function formatVoiceDuration(seconds: number): string {
+  const s = Math.max(0, Math.floor(seconds))
+  const m = Math.floor(s / 60)
+  const r = s % 60
+  return `${m}:${String(r).padStart(2, '0')}`
+}
+
+export function assertVoiceMemoBlobSize(blob: Blob): void {
+  if (blob.size > VOICE_MEMO_MAX_BLOB_BYTES) {
+    throw new Error('VOICE_MEMO_TOO_LARGE')
+  }
+}