Phase 664: voice-note fetch and forward IPC handlers.

Wire fetch-voice-note-blob and forward-voice-note through ui-flow to
platform fetchVoiceNoteBlob and forwardVoiceNote.

Co-authored-by: Cursor <[email protected]>

index.js

@@ -1138,6 +1138,45 @@ async function dispatchUiMessage (platform, msg, hooks = {}) {
     pushState()
     return true
   }
+  if (t === 'fetch-voice-note-blob') {
+    try {
+      const out = await platform.fetchVoiceNoteBlob(msg.noteId)
+      send({
+        type: 'voice-note-blob-fetched',
+        noteId: msg.noteId,
+        dataBase64: out?.dataBase64 || null,
+        bytes: out?.bytes || 0,
+        progress: out?.progress || null
+      })
+    } catch (err) {
+      send({
+        type: 'voice-note-blob-fetch-error',
+        noteId: msg.noteId,
+        message: err?.message || String(err)
+      })
+    }
+    return true
+  }
+  if (t === 'forward-voice-note') {
+    try {
+      const out = await platform.forwardVoiceNote({
+        messageId: msg.messageId,
+        targetChannelId: msg.targetChannelId
+      })
+      send({
+        type: 'voice-note-forwarded',
+        messageId: out?.message?.id || null,
+        targetChannelId: msg.targetChannelId
+      })
+      pushState()
+    } catch (err) {
+      send({
+        type: 'voice-note-forward-error',
+        message: err?.message || String(err)
+      })
+    }
+    return true
+  }
   if (t === 'stage-attachment') {
     const att = await platform.stageAttachment({
       data: fromBase64(msg.dataBase64),