Refactor station filtering from WFWX API

**Describe the task**
Refactor code so that all station filtering is done using RSQL query when making the get stations request to the WFWX API.

Right now we're doing an awkward mix of some RSQL filtering, and some Python-based filtering on the query response.

**Acceptance Criteria**
- [ ] all station filtering is performed by RSQL queries on WFWX API
- [ ] no station filtering is done by Python

**Additional context**
- we currently have backend Python code to filter out stations that aren't active (which is already being done by RSQL when making the request), and to filter out stations with missing lat/long coords - this part should be built into RSQL. See `api/app/wildfire_one.py`
- there may be additional filtering required

Start by reading api/app/wildfire_one.py and trace the get stations request to identify every station filter currently applied in Python or RSQL. Update the filtering so active stations and stations with missing latitude or longitude are handled by the WFWX API query, then verify that no station filtering remains in Python and that any additional required filters are covered.

Written by the indexing model from the issue text.