Identify user stories and design features for web-app-template version

[sgreenbury]

• [ ] Identify features/aspects from initial v0 implementation to be ported
• [ ] Consider specific requirements in various use cases for the web app
• [ ] Develop specific list of features to be developed into new issues

[sgreenbury]

Since once pattern for using popgetter involves:

1. Searching for a metric(s) of interest
2. Download selected metric(s) with additional download parameters (include geometries, bounding box, etc)

we might look to implement an interface that enables fast and interactive filtering of the metadata catalog.

With a Popgetter backend loaded storing the metadata catalog as a polars dataframe, the frontend needs to:

1. Provide a way to try different SearchParams in the frontend
2. Send the SearchParams (upon any changes) to the backend
3. Retrieve the new filtered catalog from the backend (e.g. as a JSON string)
4. Update the display of with the JSON

An example of filtering using svelte that might help with designing the search interface and also components for the metrics.