feat: discussion guide file path + initiator speaks first

1. create-discussion-channel now accepts optional discussionGuidePath
   parameter as alternative to inline discussionGuide text. Either
   one is required; file path is read at tool execution time.

2. Discussion channel speaker list now places the initiator first,
   ensuring they set context before other participants respond.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugin/index.ts

@@ -252,8 +252,13 @@ export default {
         await sendModeratorMessage(live.moderatorBotToken, channelId, discussionGuide, api.logger)
           .catch(() => undefined);
 
-        // Initialize speaker list
+        // Initialize speaker list (initiator first)
         const agentIds = await fetchVisibleChannelBotAccountIds(api, channelId, identityRegistry);
+        const initiatorIdx = agentIds.indexOf(initiatorAgentId);
+        if (initiatorIdx > 0) {
+          agentIds.splice(initiatorIdx, 1);
+          agentIds.unshift(initiatorAgentId);
+        }
         const speakers = agentIds
           .map((aid) => {
             const entry = identityRegistry.findByAgentId(aid);