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/components/PortfolioCard.astro

@@ -22,6 +22,7 @@ const { name, url, category, category_label, industry, thumbnail, description, w
   <div class="portfolio-image">
     <img src={thumbnail} alt={name} loading="lazy" />
     <div class="portfolio-overlay">
+      {what_we_did && <p class="overlay-did">{what_we_did}</p>}
       <span class="visit-btn">
         เยี่ยมชมเว็บไซต์
         <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
@@ -34,7 +35,6 @@ const { name, url, category, category_label, industry, thumbnail, description, w
     {industry && <span class="portfolio-industry">{industry}</span>}
     <span class="portfolio-category">{category_label}</span>
     <h3 class="portfolio-name">{name}</h3>
-    {what_we_did && <p class="portfolio-did">{what_we_did}</p>}
     {result && <p class="portfolio-result">→ {result}</p>}
     {!what_we_did && description && <p class="portfolio-desc">{description}</p>}
   </div>
@@ -84,8 +84,11 @@ const { name, url, category, category_label, industry, thumbnail, description, w
     inset: 0;
     background: rgba(254, 212, 0, 0.95);
     display: flex;
+    flex-direction: column;
     align-items: center;
     justify-content: center;
+    gap: 20px;
+    padding: 24px;
     opacity: 0;
     transition: opacity 0.3s ease;
   }
@@ -94,6 +97,14 @@ const { name, url, category, category_label, industry, thumbnail, description, w
     opacity: 1;
   }
 
+  .overlay-did {
+    font-size: 13px;
+    line-height: 1.6;
+    color: var(--color-black);
+    text-align: center;
+    max-width: 280px;
+  }
+
   .visit-btn {
     display: inline-flex;
     align-items: center;