feat(daemon): publish room member statistics over RPC and the CLI

The statistics parsed from the JoinRoom reply were reachable only from the
library. They answer the question `room users` already exists to ask -- who
is in here, and are they worth downloading from -- so they belong on its
output rather than behind a second call.

- proto: room.member_stats, with a RoomUserStatsDto carrying status, share
  counts, free slots and country
- SessionApi::room_member_stats, so local and remote sessions stay
  interchangeable; the status word is decoded through one shared helper
  rather than a third copy of the match
- `room users` now emits status, average_speed, shared_files,
  shared_folders, slots_free and country, each null when the server said
  nothing, documented in SKILL.md
- docs/openrpc.json regenerated from the wire types

soulseek-rs/src/ui/main_tui/mod.rs

@@ -461,6 +461,12 @@ mod tests {
         fn room_members(&self, _room: &str) -> Vec<String> {
             Vec::new()
         }
+        fn room_member_stats(
+            &self,
+            _room: &str,
+        ) -> Vec<soulseek_rs::types::RoomUserStats> {
+            Vec::new()
+        }
         fn take_room_events(&self) -> Vec<soulseek_rs::RoomEvent> {
             Vec::new()
         }