refactor: Promote handling unsigned data out of timeline

Also fixes:
- Transaction IDs leaking in event route
- Age not being set for event relations or threads
- Both of the above for search results

Notes down concern with relations table

src/api/client/room/initial_sync.rs

@@ -40,12 +40,19 @@ pub(crate) async fn room_initial_sync_route(
 		.map_ok(Event::into_format)
 		.try_collect::<Vec<_>>();
 
+	// Events are returned in body
+
 	let limit = LIMIT_MAX;
 	let events = services
 		.rooms
 		.timeline
-		.pdus_rev(None, room_id, None)
+		.pdus_rev(room_id, None)
 		.try_take(limit)
+		.and_then(async |mut pdu| {
+			pdu.1.set_unsigned(body.sender_user.as_deref());
+			// TODO: bundled aggregations
+			Ok(pdu)
+		})
 		.try_collect::<Vec<_>>();
 
 	let (membership, visibility, state, events) =