Execute due tasks

Query `pending` tasks with `run_at <= now()`. Mark as `running`, simulate execution, then `done`. Handle failures → `failed`.

Look for the periodic job that queries the database, likely using node-cron. Find the model or service for tasks and the SQL query for 'pending' tasks with 'run_at <= now()'. Implement the state transitions: pending → running → done/failed, including simulating execution and error handling. Check existing tests for task execution.

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