feat: implement locale-aware routing with [locale] dynamic segments

WARNING: This change breaks existing SEO URLs for Serbian locale.

Changes:
- Migrated from separate locale folders (src/app/en/, src/app/de/, etc.)
  to [locale] dynamic segments (src/app/[locale]/)
- Serbian is now at /sr/ instead of / (root)
- English at /en/, German at /de/, French at /fr/
- All components updated to generate locale-aware links
- Root / now redirects to /sr (307 temporary redirect)

SEO Impact:
- Previously indexed Serbian URLs (/, /products, /about, /contact)
  will now return 404 or redirect to /sr/* URLs
- This is a breaking change for SEO - Serbian pages should ideally
  remain at root (/) with only non-default locales getting prefix
- Consider implementing 301 redirects from old URLs to maintain
  search engine rankings

Technical Notes:
- next-intl v4 with [locale] structure requires ALL locales to
  have the prefix (cannot have default locale at root)
- Alternative approach would be separate folder structure per locale

src/app/[locale]/about/page.tsx

@@ -0,0 +1,128 @@
+import { getTranslations, setRequestLocale } from "next-intl/server";
+import Header from "@/components/layout/Header";
+import Footer from "@/components/layout/Footer";
+
+interface AboutPageProps {
+  params: Promise<{ locale: string }>;
+}
+
+export async function generateMetadata({ params }: AboutPageProps) {
+  const { locale } = await params;
+  return {
+    title: locale === "sr" 
+      ? "O nama - ManoonOils"
+      : "About - ManoonOils",
+    description: locale === "sr"
+      ? "Saznajte više o ManoonOils - naša priča, misija i posvećenost prirodnoj lepoti."
+      : "Learn more about ManoonOils - our story, mission, and commitment to natural beauty.",
+  };
+}
+
+export default async function AboutPage({ params }: AboutPageProps) {
+  const { locale } = await params;
+  setRequestLocale(locale);
+  const t = await getTranslations("About");
+
+  return (
+    <>
+      <Header locale={locale} />
+      <main className="min-h-screen bg-white">
+        <div className="pt-[104px]">
+          <div className="container py-12 md:py-16">
+            <div className="max-w-2xl mx-auto text-center">
+              <span className="text-xs uppercase tracking-[0.2em] text-[#666666] mb-3 block">
+                {t("subtitle")}
+              </span>
+              <h1 className="text-4xl md:text-5xl font-medium tracking-tight">
+                {t("title")}
+              </h1>
+            </div>
+          </div>
+        </div>
+
+        <div className="relative h-[400px] md:h-[500px] overflow-hidden">
+          <img
+            src="https://images.unsplash.com/photo-1608571423902-eed4a5ad8108?q=80&w=2000&auto=format&fit=crop"
+            alt={locale === "sr" ? "Proizvodnja prirodnih ulja" : "Natural oils production"}
+            className="w-full h-full object-cover"
+          />
+          <div className="absolute inset-0 bg-black/20" />
+        </div>
+
+        <section className="py-16 md:py-24">
+          <div className="container">
+            <div className="max-w-3xl mx-auto">
+              <div className="mb-16">
+                <p className="text-xl md:text-2xl text-[#1a1a1a] leading-relaxed mb-8">
+                  {t("intro")}
+                </p>
+                <p className="text-[#666666] leading-relaxed">
+                  {t("intro2")}
+                </p>
+              </div>
+
+              <div className="grid grid-cols-1 md:grid-cols-2 gap-8 md:gap-12 mb-16">
+                <div className="p-6 bg-[#f8f9fa]">
+                  <h3 className="text-lg font-medium mb-3">
+                    {t("naturalIngredients")}
+                  </h3>
+                  <p className="text-[#666666] text-sm leading-relaxed">
+                    {t("naturalIngredientsDesc")}
+                  </p>
+                </div>
+                <div className="p-6 bg-[#f8f9fa]">
+                  <h3 className="text-lg font-medium mb-3">
+                    {t("crueltyFree")}
+                  </h3>
+                  <p className="text-[#666666] text-sm leading-relaxed">
+                    {t("crueltyFreeDesc")}
+                  </p>
+                </div>
+                <div className="p-6 bg-[#f8f9fa]">
+                  <h3 className="text-lg font-medium mb-3">
+                    {t("sustainablePackaging")}
+                  </h3>
+                  <p className="text-[#666666] text-sm leading-relaxed">
+                    {t("sustainablePackagingDesc")}
+                  </p>
+                </div>
+                <div className="p-6 bg-[#f8f9fa]">
+                  <h3 className="text-lg font-medium mb-3">
+                    {t("handcraftedQuality")}
+                  </h3>
+                  <p className="text-[#666666] text-sm leading-relaxed">
+                    {t("handcraftedQualityDesc")}
+                  </p>
+                </div>
+              </div>
+
+              <div className="text-center py-12 border-t border-b border-[#e5e5e5]">
+                <span className="text-caption text-[#666666] mb-4 block">
+                  {t("mission")}
+                </span>
+                <blockquote className="text-2xl md:text-3xl font-medium tracking-tight">
+                  &ldquo;{t("missionQuote")}&rdquo;
+                </blockquote>
+              </div>
+
+              <div className="mt-16">
+                <h2 className="text-2xl font-medium mb-6">
+                  {t("handmadeTitle")}
+                </h2>
+                <p className="text-[#666666] leading-relaxed mb-6">
+                  {t("handmadeText1")}
+                </p>
+                <p className="text-[#666666] leading-relaxed">
+                  {t("handmadeText2")}
+                </p>
+              </div>
+            </div>
+          </div>
+        </section>
+      </main>
+      <div className="pt-16">
+        <Footer locale={locale} />
+      </div>
+    </>
+  );
+}