SEO: rewrite meta descriptions, add FAQ schema, add CTA box to all articles

- Rewrite meta descriptions on 4 high-impression articles (churn, compliance, data quality, ecommerce)
- Fix data-quality-validation-pipelines title & description to capture zero-click statistical validation queries
- Add FAQPage schema to churn prediction and data quality articles
- Add service CTA box to article-footer.php (appears on all blog articles)
- Add responsive CSS for CTA box in main.css

assets/css/main.css

@@ -4506,3 +4506,65 @@ body { font-size: 17px; }
 }
 
 /* ===== END VISUAL FIXES 2026-02-11 ===== */
+
+/* === Article CTA Box (SEO update Feb 2026) === */
+.article-cta {
+    background: linear-gradient(135deg, #1a3c5e 0%, #2a5f8f 100%);
+    border-radius: 12px;
+    margin: 2.5rem 0;
+    padding: 2rem 2.5rem;
+}
+.article-cta .cta-inner {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    gap: 2rem;
+    flex-wrap: wrap;
+}
+.article-cta .cta-text h3 {
+    color: #fff;
+    font-size: 1.4rem;
+    margin: 0 0 0.5rem;
+}
+.article-cta .cta-text p {
+    color: rgba(255,255,255,0.85);
+    font-size: 0.95rem;
+    margin: 0;
+    max-width: 520px;
+}
+.article-cta .cta-actions {
+    display: flex;
+    gap: 1rem;
+    flex-shrink: 0;
+    flex-wrap: wrap;
+}
+.article-cta .btn-primary {
+    background: #f59e0b;
+    color: #1a1a1a;
+    border: none;
+    padding: 0.75rem 1.5rem;
+    border-radius: 6px;
+    font-weight: 700;
+    text-decoration: none;
+    white-space: nowrap;
+    transition: background 0.2s;
+}
+.article-cta .btn-primary:hover { background: #fbbf24; }
+.article-cta .btn-secondary {
+    background: transparent;
+    color: #fff;
+    border: 2px solid rgba(255,255,255,0.6);
+    padding: 0.75rem 1.5rem;
+    border-radius: 6px;
+    font-weight: 600;
+    text-decoration: none;
+    white-space: nowrap;
+    transition: border-color 0.2s;
+}
+.article-cta .btn-secondary:hover { border-color: #fff; }
+@media (max-width: 640px) {
+    .article-cta { padding: 1.5rem; }
+    .article-cta .cta-inner { flex-direction: column; }
+    .article-cta .cta-actions { width: 100%; }
+    .article-cta .btn-primary, .article-cta .btn-secondary { text-align: center; flex: 1; }
+}