Add date filter

[SplittyDev]

Possible implementations:

• ?filter[startDate]=2024-08-11T02:00:00.000Z
• ?filter[startDate]=2024-08-10T00:00:00.000Z&filter[endDate]=2024-08-11T00:00:00.000Z
• ?filter[windowSize]=30 (filter window size in days)

As a human, the window size seems to be the easiest to use. But in a real-world analysis client, the developer would probably want explicit control over the dates, so I'm guessing the startDate and endDate thing would probably be best.