Currently, demand rules only support hourly intervals. To express a constant demand from 9:00 to 17:00, you have to enumerate up to 16 separate intervals; one per hour (or per 30 minutes). This is verbose and error-prone.

We'd like demand intervals to support arbitrary durations, so a single interval like "startDateTime": "2025-12-04T09:00:00Z", "endDateTime": "2025-12-04T17:00:00Z" can express the same thing.

The demand should be enforced at every point within the interval, not just at the start.