@CivicSignal - Sources: Improve implementation of collected stories chart

[m453h]

The Collected Stories Chart currently uses regular time intervals to render dates on the x-axis. However, when data points are at irregular intervals, this approach leads to inaccuracies in how the dates are displayed.

A solution has been implemented by filling missing dates with zero values to maintain regular intervals. While this works, an ideal approach would be to plot only the dates with actual data.