fix: display reply indicators for received DM replies

[claudespiral]

Summary

Populates replyMetadata when saving DM messages that contain repliesToMessageId, enabling the existing reply display UI to show "Replying to X".

Problem

For Quorum DMs, the relay hub only sees encrypted blobs (E2E encryption via X3DH + Double Ratchet). Unlike Farcaster where the server returns inReplyTo with full context, Quorum's API only returns the message ID reference inside encrypted content.

The mobile app has full support for displaying reply indicators (MessagesList.tsx checks replyToAuthor), but replyMetadata was never being populated for DMs.

Solution

In mmkvAdapter.saveMessage(), after loading existing messages, look up the parent message and populate replyMetadata:

if (content?.repliesToMessageId && !message.replyMetadata) {
  const parentMessage = messages.find((m) => m.messageId === content.repliesToMessageId);
  if (parentMessage?.content?.senderId) {
    message.replyMetadata = {
      parentAuthor: parentContent.senderId,
      parentChannelId: parentMessage.channelId,
    };
  }
}

Testing

• Unit tests verify the logic handles: normal replies, non-replies, missing parents, existing metadata, malformed parents
• Lint passes

Edge Cases

• Parent message not loaded yet → replyMetadata stays undefined (graceful degradation)
• Parent message deleted → same graceful handling
• Existing replyMetadata → not overwritten