feat: Discord-based agent wakeup replacing spawn

New wakeup flow:
1. Create private Discord channel for the agent
2. Send wakeup message with slot context + workflow reference
3. If Dirigent detected (globalThis.__dirigent), create work-type channel
4. Fallback to api.spawn if Discord not configured

New config fields: discordBotToken, discordGuildId
New file: plugin/calendar/discord-wakeup.ts

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

plugin/openclaw.plugin.json

@@ -63,6 +63,14 @@
       "managedMonitor": {
         "type": "string",
         "description": "Absolute path to an installed HarborForge.Monitor binary managed by this plugin installer. If set, gateway_start/gateway_stop hooks will start/stop the monitor process automatically."
+      },
+      "discordBotToken": {
+        "type": "string",
+        "description": "Discord bot token for agent wakeup. Used to create private channels and send wakeup messages. Set to the same value as Dirigent moderator bot token."
+      },
+      "discordGuildId": {
+        "type": "string",
+        "description": "Discord guild ID where wakeup channels are created."
       }
     }
   }