v2 phase 4+5: Discord via Chat SDK, expanded MCP tools, message seq IDs

- Chat SDK bridge + Discord adapter (gateway listener, message routing)
- MCP tools refactored into modular structure: core (send_message, send_file,
  edit_message, add_reaction), scheduling (schedule/list/cancel/pause/resume
  tasks), interactive (ask_user_question, send_card), agents (send_to_agent)
- Message seq IDs: shared integer sequence across messages_in/out so agents
  see small numeric IDs instead of platform snowflakes
- busy_timeout=5000 for session DB (poll loop + MCP server concurrent access)
- Always copy agent-runner source to fix stale cache when non-index files change
- Seed script for Discord testing, e2e test script

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

container/agent-runner/src/formatter.ts

@@ -67,7 +67,8 @@ function formatChatMessages(messages: MessageInRow[]): string {
     const sender = content.sender || content.author?.fullName || content.author?.userName || 'Unknown';
     const time = formatTime(msg.timestamp);
     const text = content.text || '';
-    lines.push(`<message sender="${escapeXml(sender)}" time="${time}">${escapeXml(text)}</message>`);
+    const idAttr = msg.seq != null ? ` id="${msg.seq}"` : '';
+    lines.push(`<message${idAttr} sender="${escapeXml(sender)}" time="${time}">${escapeXml(text)}</message>`);
   }
   lines.push('</messages>');
   return lines.join('\n');
@@ -78,7 +79,8 @@ function formatSingleChat(msg: MessageInRow): string {
   const sender = content.sender || content.author?.fullName || content.author?.userName || 'Unknown';
   const time = formatTime(msg.timestamp);
   const text = content.text || '';
-  return `<message sender="${escapeXml(sender)}" time="${time}">${escapeXml(text)}</message>`;
+  const idAttr = msg.seq != null ? ` id="${msg.seq}"` : '';
+  return `<message${idAttr} sender="${escapeXml(sender)}" time="${time}">${escapeXml(text)}</message>`;
 }
 
 function formatTaskMessage(msg: MessageInRow): string {