Server-side scenario execution: new Rudder.Core.dll, realtime/planstore glue removed

- Rudder.Core.dll rebuilt from csharp-sdk effects rewrite (96,768 bytes)
- Realtime/ adapters, UnityRealtimeTransportFactory, UnityPlanStateStore,
  UnityPlanScheduler, WebGL jslib and RealtimeUrl config deleted (with .meta)
- Scenarios sample rewired to client.Effects; samples login path updated
- AGENTS.md/README/CHANGELOG/package docs + agent skill updated; realtime.md skill doc removed

Packages/rudder.sdk/package.json

@@ -1,8 +1,8 @@
 {
   "name": "rudder.sdk",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "displayName": "Rudder SDK",
-  "description": "LiveOps SDK for Unity — player auth, remote config, stores, inventory, leaderboards, scenarios, realtime.",
+  "description": "LiveOps SDK for Unity — player auth, remote config, stores, inventory, leaderboards, scenarios.",
   "unity": "6000.0",
   "author": {
     "name": "Rudder",
@@ -15,5 +15,12 @@
   "documentationUrl": "https://app.rudder.build",
   "publishConfig": {
     "registry": "https://hub.rudder.build/api/packages/rudder/npm/"
-  }
+  },
+  "samples": [
+    {
+      "displayName": "Feature Samples",
+      "description": "Small scenes that show one Rudder API each: authentication, remote config, storage, stores and inventory, leaderboards, and scenarios.",
+      "path": "Samples~"
+    }
+  ]
 }