Show country names consistently in filters and sightings Parent: #158 ## Description The country filter shows full names such as “Norway”, while sighting results show country codes such as “NO”. ## Tasks - Use a shared country-code-to-name formatter in filters, results and detail views. - Preserve a clear indication when the country is missing or uncertain. - Add tests for known, unknown and missing country codes. ## Done when A country is displayed consistently as a readable name throughout the app.