feat: implement multi-message mode and shuffle mode features

- Add multi-message mode with start/end/prompt markers
- Implement turn order shuffling with /turn-shuffling command
- Add channel mode state management
- Update hooks to handle multi-message mode behavior
- Update plugin config with new markers
- Update TASKLIST.md with completed tasks

plugin/openclaw.plugin.json

@@ -25,7 +25,10 @@
       "enableDirigentPolicyTool": { "type": "boolean", "default": true },
       "enableDebugLogs": { "type": "boolean", "default": false },
       "debugLogChannelIds": { "type": "array", "items": { "type": "string" }, "default": [] },
-      "moderatorBotToken": { "type": "string" }
+      "moderatorBotToken": { "type": "string" },
+      "multiMessageStartMarker": { "type": "string", "default": "↗️" },
+      "multiMessageEndMarker": { "type": "string", "default": "↙️" },
+      "multiMessagePromptMarker": { "type": "string", "default": "⤵️" }
     },
     "required": ["noReplyProvider", "noReplyModel"]
   }