docs: Campaign LA — pinned launch-contract schema COMMITTED into plan LA1

The LA3 Opus review process note was right: the contract both sides
implement lived only in orchestrator prompts, which is exactly the drift
mode the pin exists to prevent (and it produced the paths-key CRITICAL).
The schema, field rules, probe-mode discriminator, and status vocabulary
are now a binding plan section; amendments change this text first,
implementations second. Ledger: LA3 fix round dispatched.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/AcDream.App.Tests/Net/LiveSessionShutdownIntegrationTests.cs

@@ -97,6 +97,7 @@ public sealed class LiveSessionShutdownIntegrationTests
             RuntimeGenerationToken retiringGeneration) { }
         public void ReportConnecting(string host, int port, string user) { }
         public void ReportConnected() { }
+        public void ReportRoster(LiveSessionRosterReport roster) { }
         public void ApplySelectedCharacter(LiveSessionCharacterSelection selection) { }
         public void ApplyEnteredWorld(LiveSessionCharacterSelection selection) { }
         public void DetachSession(WorldSession session) { }