Server-side scenario execution: thin effects client replaces local engine

- engine/ (DagWalker, sessions, IndexedDbPlanStore) deleted; server owns the graph
- trigger/callback/counter carry PendingEffect; GET /sdk/v1/scenarios/pending polled
  (30s jittered heartbeat paused on hidden tab + wait-deadline timers)
- client.effects public API unchanged (done/buy/dismiss/end/claim/battlepass/quest)
- planStateStore removed; loginEvent kept; reconcile() makes server the source of truth
- generated models regenerated; skills/README/CHANGELOG updated

test/e2e-prod/_setup/harness.ts

@@ -9,11 +9,6 @@ import { readArtifact } from './artifact.js';
 import type { SeedArtifact } from './types.js';
 
 type RuntimeOptions = {
-  planStateStore?: {
-    state: string | null;
-    load(): Promise<void>;
-    save(state: string | null): Promise<void>;
-  } | null;
   loginEvent?: string | null;
 };
 
@@ -52,7 +47,7 @@ export function createInMemoryTokenStore(): TokenStore {
 /** A client with no auth yet (in-memory tokens, no IndexedDB persistence). */
 export function makeProdClient<TConfig extends RemoteConfigShape = RemoteConfigShape>(
   artifact: SeedArtifact = loadArtifact(),
-  runtime: RuntimeOptions = { planStateStore: null, loginEvent: null },
+  runtime: RuntimeOptions = { loginEvent: null },
 ): RudderClient<TConfig> {
   return new RudderClient<TConfig>({
     baseUrl: artifact.baseUrl,