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/RudderClient.test.ts

@@ -148,7 +148,7 @@ describe('lazy scenario runtime', () => {
     const client = new RudderClient({
       baseUrl: 'https://api.example.com',
       projectKey: 'proj_123',
-      runtime: { planStateStore: null, loginEvent: null },
+      runtime: { loginEvent: null },
     });
     const internals = client as unknown as {
       scenarioRuntime: unknown;
@@ -163,7 +163,7 @@ describe('lazy scenario runtime', () => {
     const client = new RudderClient({
       baseUrl: 'https://api.example.com',
       projectKey: 'proj_123',
-      runtime: { planStateStore: null }, // default loginEvent: player_login
+      runtime: {},
     });
 
     const notifications: string[] = [];
@@ -182,18 +182,18 @@ describe('lazy scenario runtime', () => {
       }
       if (path === '/sdk/v1/scenarios/trigger') {
         return Promise.resolve(new Response(JSON.stringify({
-          plans: [{
-            planId: 'plan-1',
-            scenarioId: 'scenario-1',
-            userId: 'user-1',
-            startNodeId: 'start',
+          effects: [{
             runId: 'run-1',
-            nodes: [{ id: 'start', type: 'notification', data: { message: 'Welcome!' } }],
-            edges: [],
-            boundaryNodes: [],
+            scenarioId: 'scenario-1',
+            nodeId: 'start',
+            type: 'notification',
+            data: { message: 'Welcome!' },
           }],
         }), { status: 200 }));
       }
+      if (path === '/sdk/v1/scenarios/pending') {
+        return Promise.resolve(new Response(JSON.stringify({ effects: [] }), { status: 200 }));
+      }
       if (path === '/sdk/v1/remote-configs') {
         return Promise.resolve(new Response(JSON.stringify({ configs: {} }), { status: 200 }));
       }