feat(battle-node): IMatchingBridge + MatchingBridge mint battle id + node url

SVSim.BattleNode/Bridge/BattleNodeOptions.cs

@@ -0,0 +1,10 @@
+namespace SVSim.BattleNode.Bridge;
+
+/// <summary>
+/// DI-injected options for the battle node. The web host populates these — typically
+/// nodeServerUrl is "ws://localhost:5148" matching ASPNETCORE_URLS.
+/// </summary>
+public sealed class BattleNodeOptions
+{
+    public string NodeServerUrl { get; set; } = "ws://localhost:5148";
+}