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

docs/ROADMAP.md

@@ -594,7 +594,7 @@ it, raw where it doesn't.
   - Misskey actor extras;
   - book reviews (`relatedWith`, `rating`);
   - Funkwhale and Castopod metadata;
-  - Pixelfed `place` (display only, never re-federated);
+  - ~~Pixelfed `place` (display only, never re-federated)~~ done 2026-10-04: `Post.Place`, `privapub.place`;
   - Bluesky bridging per persona.
 
 ### Sweep and statistics (T and M, planned 2026-10-03, between P6 and P7)