fix(wefax): include station JSON in Docker image and handle missing file

data/*.json was excluded by .dockerignore, so wefax_stations.json was
never copied into the container image. The volume mounts in docker-compose
only cover subdirectories (weather_sat, adsb, etc.), leaving the stations
file inaccessible at runtime — causing the /wefax/stations route to 500
and the station/frequency dropdowns to appear empty.

Also adds a graceful file-existence check in load_stations() so a missing
file logs a warning and returns an empty list instead of an unhandled
FileNotFoundError.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.dockerignore

@@ -42,7 +42,6 @@ tasks/
 instance/
 
 # data/ is a Python package — only exclude non-code files
-data/*.json
 data/*.csv
 data/*.db