Add curated essays and reading paths

Introduce a Library page and wire it into the main nav.
Add blog frontmatter fields: category, featuredEssay (default false),
and readingOrder (positive integer). Update several posts to mark
featured essays and assign readingOrder for the recommended path.

src/content/blog/after-the-silence.md

@@ -3,6 +3,8 @@ title: "After the Silence"
 description: "Reflections on what remains after a meaningful relationship ends, and how love can transform without disappearing."
 pubDate: 2026-03-04
 tags: ["love", "reflection", "healing", "relationships", "personal"]
+category: "reflection"
+featuredEssay: true
 ---
 
 When a relationship ends, the world does not become quiet immediately.