fix: prevent onboarding page scrollbar by constraining to viewport height

Change outer container from min-h-[100dvh] to h-[100dvh] and hero panel
from overflow-y-auto to overflow-hidden to prevent unwanted scrollbar
caused by ASCII animation background content.

src/renderer/components/CompanyOnboarding/OnboardingHero.tsx

@@ -42,7 +42,7 @@ export function OnboardingHero({
   }));
 
   return (
-    <div className="relative flex min-h-0 items-center justify-center overflow-y-auto px-8 py-12 md:px-16">
+    <div className="relative flex min-h-0 items-center justify-center overflow-hidden px-8 py-12 md:px-16">
       {/* Ambient gradient - subtle animated accent wash */}
       <div
         className="pointer-events-none absolute inset-0 opacity-[0.035]"

src/renderer/components/CompanyOnboarding/OnboardingWizard.tsx

@@ -187,7 +187,7 @@ export function CompanyOnboarding({
   }, [launchSummary, onDone, t]);
 
   return (
-    <div className="relative grid min-h-[100dvh] overflow-hidden bg-background md:grid-cols-[minmax(0,1fr)_540px]">
+    <div className="relative grid h-[100dvh] overflow-hidden bg-background md:grid-cols-[minmax(0,1fr)_540px]">
       {/* Drag region for macOS frameless title bar */}
       <div className="sidebar-drag absolute inset-x-0 top-0 z-10 h-[38px]" />
       <OnboardingHero