Return the universe of filter values available for a facility and invoice type
heat,
electricity, water, recharge, process, waste_water_treatment).
The response represents the universe of values that exist for that
facility + type. It is not scoped by the filters the user has already
selected — this lets the UI offer cross-filter combinations without a
cascade that hides valid options.
heat, electricity, water, recharge, process, waste_water_treatmentmanual, pdf, bulk_file,
datadis. Invoices with a NULL source are surfaced as "manual" so
the UI can offer a single “Manual” option that also matches legacy rows.