feat: Introduce site configuration management with a new Prisma model and API endpoints, and add a health check endpoint.

prisma/schema.prisma

@@ -105,3 +105,15 @@ model Tag {
 
   blogs Blog[]
 }
+
+model SiteConfig {
+  id           String   @id @default(cuid())
+  cvUrl        String?
+  linkedinUrl  String?
+  githubUrl    String?
+  twitterUrl   String?
+  heroTitle    String?
+  heroSubtitle String?
+  createdAt    DateTime @default(now())
+  updatedAt    DateTime @updatedAt
+}