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/Samples~/README.md

@@ -0,0 +1,20 @@
+# Rudder feature samples
+
+Small scenes that show one Rudder API each. Open a scene, assign a
+`RudderConfiguration` if the field is empty, press Play.
+
+| Scene | Shows |
+| --- | --- |
+| `Authentication/Authentication.unity` | `Rudder.Initialize`, `Auth.LoginWithDeviceAsync`, `Player.GetProfileAsync`, `Auth.Logout` |
+| `RemoteConfig/RemoteConfig.unity` | `RemoteConfig.LoadAsync`, `Get(key, fallback)` |
+| `Storage/Storage.unity` | `Storage.GetAsync`, `SaveAsync`, `DeleteAsync` |
+| `StoreInventory/StoreInventory.unity` | `Stores.ListAsync`, `PurchaseAsync`, `Inventory.GetAsync` |
+| `Leaderboards/Leaderboards.unity` | `Leaderboards.FindBySlug`, `SubmitAsync`, `ListAsync` |
+| `Scenarios/Scenarios.unity` | `Scenario.TriggerAsync` and `Effects.OnNotification` / `Effects.OnStoreOffer` / … |
+
+Each scene has a `Rudder` component using `Assets/LiveOpsLocal.asset`.
+Login uses the device id owned by the SDK (PlayerPrefs).
+
+Stage data that makes the later scenes interesting is listed in the project
+README (store `cozy-camp-shop`, leaderboard `cozy-collector-score`, scenario
+events `player_login` / `demo_round_finished`).