fix(battle-node): respond to InitBattle/Loaded, not InitNetwork

Pushing Matched in response to InitNetwork lands it before
MatchingInitBattle() finishes wiring up the OnReceivedEvent handler
and setting status=Connect. The client's Matched-case in
ReactionReceiveUri only transitions to StartLoad when status is
Connect at the moment of receipt; otherwise the frame is silently
dropped at the state machine and the matchmaking UI never advances.

The real connect-handshake sequence (per MatchingNetworkConnectChecker
+ Matching.cs):
  1. WS opens.
  2. Client emits InitNetwork (cat=general).
  3. Server replies InitNetwork ack → _initNetworkSuccess = true.
  4. MatchingInitBattle: status=Connect; emit InitBattle; subscribe
     OnReceivedEvent matching handler.
  5. Server replies Matched → status=StartLoad, StartBattleLoad.
  6. Asset load done → client emits Loaded.
  7. Server replies BattleStart + Deal → status=Prepared, GotoBattle.

Add AwaitingInitBattle phase, gate Matched on InitBattle receipt, and
gate BattleStart+Deal on Loaded receipt. Update dispatch and
integration tests to walk the new sequence; InitBattle's wire cat is
Matching(2), not Battle(1).

Caught during v1 smoke walkthrough — battle-traffic.ndjson showed the
client receiving Matched/BattleStart at sub-millisecond gaps after
InitNetwork ack, but never advancing past matchmaking.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.BattleNode/Sessions/BattleSessionPhase.cs

@@ -7,6 +7,7 @@ namespace SVSim.BattleNode.Sessions;
 public enum BattleSessionPhase
 {
     AwaitingInitNetwork,
+    AwaitingInitBattle,
     AwaitingLoaded,
     AwaitingSwap,
     AfterReady,