Add built-in scheduler with group-scoped tasks

- Custom nanoclaw MCP server with scheduling tools (schedule_task,
  list_tasks, get_task, update_task, pause/resume/cancel_task, send_message)
- Tasks run as full agents in their group's context
- Support for cron, interval, and one-time schedules
- Task run logging with duration and results
- Main channel has Bash access for admin tasks (query DB, manage groups)
- Other groups restricted to file operations only
- Updated docs and requirements

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/config.ts

@@ -1,8 +1,10 @@
 export const ASSISTANT_NAME = process.env.ASSISTANT_NAME || 'Andy';
 export const POLL_INTERVAL = 2000;
+export const SCHEDULER_POLL_INTERVAL = 60000; // Check for due tasks every minute
 export const STORE_DIR = './store';
 export const GROUPS_DIR = './groups';
 export const DATA_DIR = './data';
+export const MAIN_GROUP_FOLDER = 'main';
 
 export const TRIGGER_PATTERN = new RegExp(`^@${ASSISTANT_NAME}\\b`, 'i');
 export const CLEAR_COMMAND = '/clear';