feat: Add wrapper component support to onboarding orchestrator

- Add wrapper property to OnboardingOrchestratorService
- Update onboarding/yield component to render wrapper using lazy-engine-component
- Clean up onboard.hbs template to remove styling constraints
- Enable extensions to provide custom wrapper components for onboarding flows

console/app/components/onboarding/yield.hbs

@@ -1,7 +1,9 @@
 <section class="onboarding step-host">
     {{#if this.initialized}}
-        {{#if this.currentComponent}}
-            {{component this.currentComponent context=this.context orchestrator=this.orchestrator brand=@brand}}
+        {{#if this.orchestrator.wrapper}}
+            {{component (lazy-engine-component this.orchestrator.wrapper) currentStepComponent=this.currentComponent context=this.context orchestrator=this.orchestrator brand=@brand}}
+        {{else if this.currentComponent}}
+            {{component (lazy-engine-component this.currentComponent) context=this.context orchestrator=this.orchestrator brand=@brand}}
         {{/if}}
     {{else}}
         <div class="flex items-center justify-center min-h-24">

console/app/services/onboarding-orchestrator.js

@@ -7,6 +7,7 @@ export default class OnboardingOrchestratorService extends Service {
     @service onboardingContext;
 
     @tracked flow = null;
+    @tracked wrapper = null;
     @tracked current = null;
     @tracked history = [];
     @tracked sessionId = null;
@@ -15,6 +16,7 @@ export default class OnboardingOrchestratorService extends Service {
         const flow = this.onboardingRegistry.getFlow(flowId ?? this.onboardingRegistry.defaultFlow);
         if (!flow) throw new Error(`Onboarding flow '${flowId}' not found`);
         this.flow = flow;
+        this.wrapper = flow.wrapper || null;
         this.sessionId = opts.sessionId || null;
         this.history = [];
         this.goto(flow.entry);

console/app/templates/onboard.hbs

@@ -1,6 +1,3 @@
-<div class="flex items-center justify-center h-screen min-h-screen px-4 py-12 bg-gray-50 dark:bg-gray-900 sm:px-6 lg:px-8 overflow-y-scroll">
-    <div class="w-full max-w-md h-screen flex items-center justify-center py-4">
-        {{outlet}}
-    </div>
-    <Spacer @height="300px" />
+<div class="onboard-route-wrapper">
+    {{outlet}}
 </div>