feat: implement programmatic SEO for solutions pages

- Add 10 oil-for-concern solution pages with localized slugs
- Support 4 languages: sr, en, de, fr with proper canonical URLs
- Add solutions hub, by-concern, and by-oil directory pages
- Filter bundle products from solutions pages
- Add hideLangSwitcher prop to Header component
- Update translations for all languages
- Fix canonical URLs to include locale prefix

src/components/programmatic-seo/OilForConcernPage.tsx

@@ -30,7 +30,7 @@ export function OilForConcernPageTemplate({ page, locale, basePath, products }:
   
   return (
     <>
-      <Header locale={locale} />
+      <Header locale={locale} hideLangSwitcher={true} />
       <main className="min-h-screen bg-white">
         <section className="bg-[#FAF9F7] pt-[180px] lg:pt-[200px] pb-16">
           <div className="max-w-[1400px] mx-auto px-4 sm:px-6 lg:px-8">