Simplify hero backgrounds and add entrance animations

- Replace animated blob/wave/noise backdrop with clean static gradient
  (radial ellipse highlights + linear fade) in hero-motion-backdrop
- Remove all framer-motion from background layer; delete unused CSS
  classes: hero-blob, hero-sheet-glow, hero-sheet-wave, hero-sheet-noise,
  hero-title-shift keyframe, and responsive blob media queries
- Add framer-motion stagger entrance to HeroContentMotion, HeroMotionItem,
  and HeroTitle (slide-up + fade on mount)
- Refactor coming-soon page to use HeroContentMotion/HeroMotionItem
  instead of MotionFade (whileInView unreliable above the fold)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/[locale]/(site)/portfolio/[slug]/page.tsx

@@ -61,10 +61,7 @@ export default async function PortfolioItemPage({
 
   return (
     <>
-      <PageHero
-        title={getLocalizedValue(item.title, localeKey)}
-        description={getLocalizedValue(item.summary, localeKey)}
-      />
+      <PageHero />
 
       <Container size="wide" className="pb-12 lg:pb-16">
         <PortfolioProjectDetail