Versus map size on the match page; the size sets the number of seats

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/settings.rs

@@ -163,6 +163,7 @@ pub struct Settings {
     pub hints: bool,
     pub difficulty: u8, // rival masters in free games: 0 easy, 1 medium, 2 hard
     pub map_w: usize, // size of new maps (64..256)
+    pub match_size: usize, // versus matches: the map is match_size x match_size (see lobby::seats_for)
     pub map_h: usize,
     pub surface: bool, // new free games: the eastern half lies above ground (forest)
     pub events: bool,  // random events in free games and versus matches
@@ -201,6 +202,7 @@ impl Default for Settings {
             hints: true,
             difficulty: 1,
             map_w: 64,
+            match_size: 128,
             map_h: 64,
             surface: false,
             events: true,