Event Log Analyzer

You're given a list of event logs. Each event has:

{
    "timestamp": "2024-02-12T10:30:00Z",
    "event_type": "click",
    "user_id": "user123",
    "properties": {"page": "/home"}
}

Part 1: summarize(events) — Group by event_type, count occurrences. Returns: [{"event_type": "click", "count": 3}, ...]

Part 2: most_active_user(events) — Return the user_id with the most events.

Part 3: events_per_hour(events) — Return a dict mapping hour (0-23) to event count.