fix: correct business framing - website design & development is primary, email is secondary

Update hello-world post, homepage, about page, and zh landing to say
website design & development (primary) + email hosting (side offering),
not 'email-hosting business'.

src/pages/index.astro

@@ -15,8 +15,8 @@ const posts = (await getCollection('posts', isEn))
     <p>
       A full-stack developer and DevOps engineer based in Malaysia. I build web
       apps (PHP/CodeIgniter, Java/Spring, TypeScript/React), self-host a
-      ~140-container homelab, and run a small email-hosting business for
-      Malaysian SMEs. I write here about what I learn and ship.
+      ~140-container homelab, and run a website design & development business
+      for Malaysian SMEs. I write here about what I learn and ship.
     </p>
     <p>
       <a href="/about/">More about me</a>