Update insulation brand pages (Armaflex, Aeroflex, Maxflex)

- Added 3 new brand pages: armflex.astro, aeroflex.astro, maxflex.astro
- Updated hero images with product photos from 3t-insulation.com
- Enhanced content with product specifications and benefits
- Added standard certifications (FM Approved, UL 94, GREENGUARD)
- Added product gallery sections
- Shortened menu names to brand only (Armaflex, Aeroflex, Maxflex)
- Removed old ฉนวนหุ้มท่อ.astro page
- Updated Header and BaseLayout navigation
- Downloaded product images for all 3 brands

public/images/pipe-coupling/coupling.svg

@@ -0,0 +1,6 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="400" height="400" viewBox="0 0 400 400">
+  <rect width="400" height="400" fill="#65a30d"/>
+  <text x="200" y="100" text-anchor="middle" fill="white" font-family="sans-serif" font-size="24" font-weight="600">Pipe Coupling</text>
+  <ellipse cx="200" cy="250" rx="90" ry="30" fill="none" stroke="white" stroke-width="8"/>
+  <ellipse cx="200" cy="250" rx="60" ry="18" fill="none" stroke="white" stroke-width="4"/>
+</svg>