Pandas Clean, Merge, Aggregate

Write a Python function using Pandas to clean, merge, and aggregate two disparate client datasets with mismatched timestamps.

For this SQL version, use the supplied client registry and two datasets. Exclude records missing timestamps or metric values, align valid records by calendar date, and preserve valid dataset records even when no registry match exists.

Output

1. One row per client and event date.
2. Return client_id, client_name, event_date, dataset_a_value, dataset_b_value, total_value, and total_events.
3. Treat missing source values as zero, order by event_date ascending and client_id ascending.