Initial implementation of mcq — document reading queue

Single-binary service: push raw markdown via REST/gRPC API, read rendered
HTML through mobile-friendly web UI. MCIAS auth on all endpoints, SQLite
storage, goldmark rendering with GFM and syntax highlighting.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/render/render.go

@@ -0,0 +1,50 @@
+package render
+
+import (
+	"bytes"
+	"fmt"
+
+	chromahtml "github.com/alecthomas/chroma/v2/formatters/html"
+	"github.com/yuin/goldmark"
+	highlighting "github.com/yuin/goldmark-highlighting/v2"
+	"github.com/yuin/goldmark/extension"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer/html"
+)
+
+// Renderer converts markdown to HTML using goldmark.
+type Renderer struct {
+	md goldmark.Markdown
+}
+
+// New creates a Renderer with GFM, syntax highlighting, and heading anchors.
+func New() *Renderer {
+	md := goldmark.New(
+		goldmark.WithExtensions(
+			extension.GFM,
+			highlighting.NewHighlighting(
+				highlighting.WithStyle("github"),
+				highlighting.WithFormatOptions(
+					chromahtml.WithClasses(true),
+				),
+			),
+		),
+		goldmark.WithParserOptions(
+			parser.WithAutoHeadingID(),
+		),
+		goldmark.WithRendererOptions(
+			html.WithUnsafe(),
+		),
+	)
+
+	return &Renderer{md: md}
+}
+
+// Render converts markdown source to HTML.
+func (r *Renderer) Render(source []byte) (string, error) {
+	var buf bytes.Buffer
+	if err := r.md.Convert(source, &buf); err != nil {
+		return "", fmt.Errorf("render markdown: %w", err)
+	}
+	return buf.String(), nil
+}