refactor(battle-node): remove ScriptedBotParticipant and dev-affordance wiring

Deletes the scripted opponent and every entry point that created a
BattleType.Scripted session (the ?scripted=1 query opt-in, the
SoloDefaultsToScripted toggle, the resolver short-circuit, the WS handler case,
the bridge validation arm). Real two-client PvP and the Bot matchmaking-timeout
fallback are untouched. ResolveAsync drops its scriptedOptIn parameter.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

SVSim.BattleNode/Bridge/MatchingBridge.cs

@@ -47,9 +47,6 @@ public sealed class MatchingBridge : IMatchingBridge
             case BattleType.Bot:
                 if (p2 is not null) throw new ArgumentException("Bot must have p2==null.", nameof(p2));
                 break;
-            case BattleType.Scripted:
-                // p2 currently null; future server-driven bot will populate it.
-                break;
             default:
                 throw new ArgumentOutOfRangeException(nameof(type), type, "Unknown BattleType.");
         }