Site audit fixes: metadata, download URLs, nav dropdown, CTAs, related resources

- Add metadata and h1 to homepage
- Replace all placeholder download URLs with real links
- Convert Platform nav item to dropdown with product sub-links
- Add hero CTA buttons to rover page
- Add bottom CTA section to platform page
- Add RelatedResources to junior and python pages
- Add metadata description to contact and download pages
- Update "Visit Store" to "Build Your Kit" for consistency
- Add Airtable TODO comment in contact form handler
- Update Micromelon-Py card image to VS Code screenshot

src/data/navigation.ts

@@ -5,7 +5,17 @@ export interface NavItem {
 }
 
 export const navigation: NavItem[] = [
-  { label: "Platform", href: "/platform" },
+  {
+    label: "Platform",
+    href: "/platform",
+    children: [
+      { label: "Micromelon Rover", href: "/rover" },
+      { label: "Junior", href: "/junior" },
+      { label: "Code Editor", href: "/code-editor" },
+      { label: "Python Library", href: "/python" },
+      { label: "Robot Simulator", href: "/robot-simulator" },
+    ],
+  },
   { label: "Resources", href: "/resources" },
   { label: "News", href: "/news" },
   { label: "About Us", href: "/about-us" },
@@ -30,6 +40,8 @@ export const footerNavigation = {
     { label: "Micromelon Rover", href: "/rover" },
     { label: "Code Editor", href: "/code-editor" },
     { label: "Robot Simulator", href: "/robot-simulator" },
+    { label: "Junior", href: "/junior" },
+    { label: "Python Library", href: "/python" },
   ],
   support: [
     { label: "Resources", href: "/resources" },