refactor(seo): Improve page metadata and HTML semantics

This commit updates the page metadata (title and description) from the default Next.js placeholders to be descriptive of the Opp lens application, improving SEO.

Additionally, it refactors the HTML structure for better semantics and accessibility:
- Replaced generic `div` and fragment tags with appropriate semantic elements like `main`, `article`, `li`, and `small`.
- Corrected the heading hierarchy for better document structure.
- Fixed image source paths by making them absolute to prevent broken images.

app/marketing/[id]/page.tsx

@@ -191,7 +191,7 @@ export default function Home() {
         <section className="flex flex-col gap-10 md:flex-row">
           <div className="flex flex-col gap-7 bg-[#FFF7EB] p-10 rounded-3xl md:pb-20">
             <Image
-              src={"people.svg"}
+              src={"/people.svg"}
               width={48}
               height={48}
               alt="people icon"
@@ -207,7 +207,7 @@ export default function Home() {
           </div>
           <div className="flex flex-col gap-7  bg-[#E5EFFF] p-10 rounded-3xl md:pb-20">
             <Image
-              src={"shield-tick.svg"}
+              src={"/shield-tick.svg"}
               width={48}
               height={48}
               alt="shield icon"