Add Docker deployment pipeline and site updates

- Dockerfile (multi-stage Next.js standalone build)
- docker-compose.yml for Portainer stack
- Gitea Actions workflow for CI/CD
- Runner container config (Dockerfile.runner + compose)
- next.config.ts: enable standalone output
- Site content and image updates

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

src/app/platform/page.tsx

@@ -31,7 +31,7 @@ export default function PlatformPage() {
       </section>
 
       {/* Micromelon Rover */}
-      <section className="border-t border-border bg-muted py-20">
+      <section className="bg-muted py-20">
         <Container>
           <div className="grid items-center gap-12 md:grid-cols-2">
             <div className="flex justify-center">
@@ -70,16 +70,16 @@ export default function PlatformPage() {
       <LearningPathway className="bg-white" />
 
       {/* Junior */}
-      <section className="border-t border-border bg-muted py-20">
+      <section className="bg-muted py-20">
         <Container>
           <div className="grid items-center gap-12 md:grid-cols-2">
             <div className="flex justify-center">
               <Image
-                src="/images/products/rover-render.jpg"
-                alt="Micromelon Junior app"
-                width={560}
-                height={400}
-                className="w-full max-w-lg rounded-2xl"
+                src="/images/products/junior-hero.png"
+                alt="Micromelon Junior app interface showing block-based coding"
+                width={2326}
+                height={1856}
+                className="w-full max-w-lg rounded-2xl shadow-lg"
               />
             </div>
             <div>
@@ -159,7 +159,7 @@ export default function PlatformPage() {
       </section>
 
       {/* Python Library */}
-      <section className="border-t border-border bg-muted py-20">
+      <section className="bg-muted py-20">
         <Container>
           <div className="grid items-center gap-12 md:grid-cols-2">
             <div className="flex justify-center">