Use player names in two-player briscola

Classic briscola has no partnerships: its "teams" are just the two
players, but the UI labelled them Team A/Team B.

- add is_individual_game() and GameView::player_name_for_team() to the
  model;
- the briscola table HUD reads "Alice 0 — 0 Bob (target 61)" and the
  seat panels drop the Team badge for two-player games;
- the deal summary and game-over screen name the sides and the winner;
- the waiting room and join preview hide the Team badge.

briscola a quattro and scopone keep their team labels, and the match
history table is unchanged.

web/src/pages/lobby.rs

@@ -15,8 +15,8 @@ use crate::api;
 use crate::components::card::card_back;
 use crate::components::toast::toast;
 use crate::model::{
-    fallback_game_types, AuthProvider, GameTypeInfo, JoinPreview, OptionField, OptionKind,
-    PlayerRating, User,
+    fallback_game_types, is_individual_game, AuthProvider, GameTypeInfo, JoinPreview,
+    OptionField, OptionKind, PlayerRating, User,
 };
 
 /// Human-readable label for a provider name ("google" -> "Google").
@@ -237,15 +237,20 @@ fn join_preview_panel(
         })
         .collect::<Vec<_>>();
     let seated = p.players.len();
+    let show_teams = !is_individual_game(&p.game_type);
     let players = p
         .players
         .iter()
         .map(|player| {
             let name = player.name.clone();
-            let team = player.team.as_ref().map(|t| {
-                let label = t.clone();
-                view! { span(class="badge text-bg-info ms-2") { "Team " (label) } }
-            });
+            let team = if show_teams {
+                player.team.as_ref().map(|t| {
+                    let label = t.clone();
+                    view! { span(class="badge text-bg-info ms-2") { "Team " (label) } }
+                })
+            } else {
+                None
+            };
             view! {
                 li(
                     class="list-group-item d-flex justify-content-between \