Heartbeat task parsing now respects field indentation

Heartbeat tasks in the auto-reply system now parse correctly regardless of where interval and prompt fields appear in the configuration. Previously, the parsing logic matched on field names without verifying indentation, so top-level fields appearing after a task block would overwrite the task's own correctly parsed values. This meant tasks could end up with the wrong interval or prompt entirely. The fix adds an indentation check so only properly nested fields—those indented under a task block—get captured. Configuration boundaries are now respected.