fix(products): align all-products images with product-page heroes + drop dates

## all-products.astro

Remove 2 broken product links (Poloplast, PVC + fittings) and align the
remaining 24 products with the header main menu (BaseLayout.astro):

- Reorganise categories to match the 7 header categories (ท่อพีพีอาร์,
  เครื่องเชื่อมท่อ, ระบบน้ำ, อุปกรณ์ปรับอากาศ, อุปกรณ์ดับเพลิง,
  ฉนวนหุ้มท่อ, ระบบรั้ว) instead of the old ad-hoc split
- Add Ball Jet to "อุปกรณ์ปรับอากาศ" so the page matches the menu
- Re-point 6 product images to each product page's actual hero/feature
  image so the cards show what the linked page shows:
  - HDPE, Syler, HDPE welding, PPR welding, Ball Jet, Vineman

## index.astro (homepage)

Drop the <time>...</time> block from the "บทความล่าสุด" article cards
to match the blog index (no dates, just tag chips).

src/pages/index.astro

@@ -339,9 +339,6 @@ const articles = (await getCollection('blog')).sort(
             </div>
             <div class="p-6">
               <div class="flex items-center gap-3 text-sm text-slate-500 mb-3">
-                <time datetime={article.data.published_at.toISOString().slice(0, 10)}>
-                  {article.data.published_at.toLocaleDateString('th-TH', { year: 'numeric', month: 'long', day: 'numeric' })}
-                </time>
                 {article.data.tags?.[0] && (
                   <span class="px-2.5 py-0.5 bg-primary-50 text-primary-600 rounded-full text-xs font-medium">{article.data.tags[0]}</span>
                 )}