fix: show all available filter options while filtering is active (close #695)

[justin-jiajia]

I done this by retrieving a summary of the same period without any filters. Maybe there's a more efficient way that I didn't come up with.

[muety]

While this is not optimal performance-wise since we're now loading two summaries for every filtered request, it's still the easiest and most straightforward way I can think of rn without employing a crazy lot of new changes. Should be fine. Thanks for the contribution! 👍