Add lightweight self-hosted Hugo CMS with GitHub API backend

Implements a Go-based CMS for editing Hugo posts and uploading images
via the GitHub REST API, with no database and Git as the source of truth.

Features:
- Single admin auth with bcrypt password and signed session cookies
- Dashboard, post listing with search, create/edit with EasyMDE editor
- Media library for static/uploads/ with drag-drop and clipboard paste
- Client-side autosave, unsaved changes warning, dark mode, responsive UI
- Modular packages for auth, github, posts, media, session, and handlers

Co-authored-by: codegirl007 <s.raide@gmail.com>

cms/internal/templates/renderer.go

@@ -0,0 +1,71 @@
+package templates
+
+import (
+	"embed"
+	"html/template"
+	"io"
+	"io/fs"
+	"net/http"
+	"time"
+)
+
+//go:embed all:templates
+var templateFS embed.FS
+
+//go:embed all:static
+var staticFS embed.FS
+
+// Renderer renders HTML templates with shared layout and functions.
+type Renderer struct {
+	templates *template.Template
+}
+
+// New creates a template renderer.
+func New() (*Renderer, error) {
+	funcs := template.FuncMap{
+		"formatDate": formatDate,
+		"draftBadge": draftBadgeClass,
+	}
+
+	tmpl, err := template.New("").Funcs(funcs).ParseFS(templateFS, "templates/*.html")
+	if err != nil {
+		return nil, err
+	}
+
+	return &Renderer{templates: tmpl}, nil
+}
+
+// Render executes a named template with data.
+func (r *Renderer) Render(w io.Writer, name string, data any) error {
+	return r.templates.ExecuteTemplate(w, name, data)
+}
+
+// StaticHandler serves embedded static assets.
+func StaticHandler() http.Handler {
+	sub, err := fs.Sub(staticFS, "static")
+	if err != nil {
+		panic(err)
+	}
+	return http.FileServer(http.FS(sub))
+}
+
+func formatDate(t any) string {
+	switch v := t.(type) {
+	case time.Time:
+		if v.IsZero() {
+			return "—"
+		}
+		return v.Format("Jan 2, 2006")
+	case string:
+		return v
+	default:
+		return "—"
+	}
+}
+
+func draftBadgeClass(draft bool) string {
+	if draft {
+		return "badge-draft"
+	}
+	return "badge-published"
+}