Pixelfed places: a remote post's own place, shown and never federated again

A Note's `location` that is a Place with coordinates (Pixelfed sends
them as strings) is kept in the new Post.Place and shown as
Status.privapub.place {name, latitude, longitude, country}; an edit
replaces it. An Event's location stays its own `places`, and nothing
renders a place back out. Closes the INTEROP P2 Pixelfed location gap
and the ROADMAP long-tail item.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

PrivaPub/Api/Mastodon/Mappers/MastodonMapper.cs

@@ -1,4 +1,4 @@
-using MongoDB.Entities;
+using MongoDB.Entities;
 
 using PrivaPub.Api.Mastodon.Entities;
 using PrivaPub.Api.Mastodon.Infrastructure;
@@ -457,6 +457,10 @@ namespace PrivaPub.Api.Mastodon.Mappers
 				Status = post.Event.Status,
 				Category = post.Event.Category
 			},
+			Place = post.Place == default ? default : new PrivaPubPlace
+			{
+				Name = post.Place.Name, Latitude = post.Place.Latitude, Longitude = post.Place.Longitude, Country = post.Place.Country
+			},
 			Votes = new PrivaPubVotes { Up = post.FavouritesCount, Down = post.DownvotesCount }
 		};