Add endpoint `/phrase/suggestions/location/{deviceId}/`

# Current
- (none)

# Expected
1. The client posts its device information to `/device/`
2. The server responses list of phrases, which is suited for that location-context: list of translations and metadata

Start by locating the existing /device/ endpoint and the server's phrase-related handlers. Trace how device information is received, then determine how the new endpoint should return location-suited phrases with translations and metadata; done means the endpoint accepts a deviceId and produces that response.

Written by the indexing model from the issue text.