feat: add SEO utility functions smartTruncate and buildBreadcrumbList (Task 1)

lib/utils/seo.ts

@@ -0,0 +1,33 @@
+/**
+ * Truncate text at a word boundary, appending ellipsis if cut.
+ * Guarantees the result never breaks a word in half.
+ */
+export function smartTruncate(text: string, maxLen: number): string {
+  if (text.length <= maxLen) return text
+  const truncated = text.slice(0, maxLen)
+  const lastSpace = truncated.lastIndexOf(" ")
+  return lastSpace > 0 ? truncated.slice(0, lastSpace) + "..." : truncated + "..."
+}
+
+/** Breadcrumb segment — name and absolute URL */
+export interface BreadcrumbSegment {
+  name: string
+  url: string
+}
+
+/**
+ * Build a Schema.org BreadcrumbList from ordered segments.
+ * Position is 1-based per Schema.org spec.
+ */
+export function buildBreadcrumbList(segments: BreadcrumbSegment[]) {
+  return {
+    "@context": "https://schema.org",
+    "@type": "BreadcrumbList",
+    itemListElement: segments.map((seg, i) => ({
+      "@type": "ListItem",
+      position: i + 1,
+      name: seg.name,
+      item: seg.url,
+    })),
+  }
+}