feat(portfolio): move what_we_did to hover overlay + show 4 specific clients

Per user spec:
1. Home portfolio now shows only 4 specific clients in order:
   Dataroot → Jet Industries → ทวนทอง 99 → สำนักงานกฎหมาย ตถาตา
   (was filtering by featured: true, now filters by slug)

2. PortfolioCard: what_we_did moved from always-visible to
   yellow hover overlay (shown above "เยี่ยมชมเว็บไซต์" button).
   All cards now have uniform layout:
   - Default: image + name + industry + category + result
   - On hover (desktop): overlay shows what_we_did text + visit button
   - No hover effect on mobile (tap navigates to URL)

3. Added what_we_did + result to 3 cards that were missing them:
   - Jet Industries, ทวนทอง 99, สำนักงานกฎหมาย ตถาตา

Co-Authored-By: Claude <noreply@anthropic.com>

src/pages/index.astro

@@ -69,7 +69,12 @@ const dedupedServices = (() => {
 })();
 
 const portfolio = await getCollection('portfolio');
-const featuredPortfolio = portfolio.filter(p => p.data.featured).slice(0, 4);
+const featuredPortfolio = portfolio.filter(p =>
+  ['dataroot', 'jet-industries', 'tuanthong', 'lawyernoom'].includes(p.id)
+).sort((a, b) => {
+  const order = ['dataroot', 'jet-industries', 'tuanthong', 'lawyernoom'];
+  return order.indexOf(a.id) - order.indexOf(b.id);
+});
 ---
 
 <Base title="MoreminiMore - ที่ปรึกษาเว็บ การตลาด และ AI สำหรับ SME ไทย">