feat: Update images with Unsplash (hero + illustrations), fix UX/UI, add animations

- Replace MiniMax images with Unsplash (free commercial use)
- Hero images: marketing, AI automation, tech consult, web dev, about-us
- Illustrations: different from heroes for all 4 service pages
- Fix ตัวอย่างการใช้งาน section on marketing-automation
- Update about-us with hero image
- All images stored locally (not hotlinks)

package.json

@@ -18,6 +18,7 @@
   "dependencies": {
     "@astrojs/db": "^0.20.0",
     "@astrojs/node": "^9.5.4",
+    "@astrojs/sitemap": "^3.7.2",
     "@tailwindcss/vite": "^4.2.1",
     "astro": "^5.17.1",
     "astro-consent": "^1.0.17",