feat: GFM + hard line breaks for single newlines

Goldmark now uses GFM extension and WithHardWraps so single
newlines in markdown render as <br> instead of collapsing.

👾 Generated with [Letta Code](https://letta.com)

Co-Authored-By: Letta Code <noreply@letta.com>

blog/store.go

@@ -10,6 +10,13 @@ import (
 	"time"
 
 	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/extension"
+	"github.com/yuin/goldmark/renderer/html"
+)
+
+var md = goldmark.New(
+	goldmark.WithExtensions(extension.GFM),
+	goldmark.WithRendererOptions(html.WithHardWraps()),
 )
 
 type Post struct {
@@ -52,7 +59,7 @@ func (s *Store) Load(dir string) error {
 		title, body, date := parseFrontMatter(raw, slug, path)
 
 		var buf bytes.Buffer
-		if err := goldmark.Convert(body, &buf); err != nil {
+		if err := md.Convert(body, &buf); err != nil {
 			continue
 		}