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/media/media.go

@@ -0,0 +1,113 @@
+package media
+
+import (
+	"context"
+	"fmt"
+	"path"
+	"sort"
+	"strings"
+
+	"github.com/codegirl-007/hugo-cms/internal/github"
+)
+
+const uploadsDir = "static/uploads"
+
+// Item represents an uploaded media file.
+type Item struct {
+	Name string `json:"name"`
+	Path string `json:"path"`
+	URL  string `json:"url"`
+	Size int    `json:"size"`
+}
+
+// Service manages media uploads via GitHub.
+type Service struct {
+	github github.Client
+}
+
+// NewService creates a media service.
+func NewService(client github.Client) *Service {
+	return &Service{github: client}
+}
+
+// List returns all files in the uploads directory.
+func (s *Service) List(ctx context.Context) ([]Item, error) {
+	items, err := s.github.ListDirectory(ctx, uploadsDir)
+	if err != nil {
+		// Directory may not exist yet.
+		if strings.Contains(err.Error(), "404") {
+			return []Item{}, nil
+		}
+		return nil, fmt.Errorf("list media: %w", err)
+	}
+
+	var media []Item
+	for _, item := range items {
+		if item.Type != "file" {
+			continue
+		}
+		media = append(media, Item{
+			Name: item.Name,
+			Path: item.Path,
+			URL:  "/uploads/" + item.Name,
+			Size: item.Size,
+		})
+	}
+
+	sort.Slice(media, func(i, j int) bool {
+		return media[i].Name < media[j].Name
+	})
+
+	return media, nil
+}
+
+// Upload saves a binary file to static/uploads/ via the GitHub API.
+func (s *Service) Upload(ctx context.Context, filename string, data []byte) (*Item, error) {
+	filename = sanitizeFilename(filename)
+	if filename == "" {
+		return nil, fmt.Errorf("invalid filename")
+	}
+
+	filePath := path.Join(uploadsDir, filename)
+	existingSHA := ""
+
+	if existing, err := s.github.GetFile(ctx, filePath); err == nil {
+		existingSHA = existing.SHA
+	}
+
+	message := fmt.Sprintf("Upload image: %s", filename)
+
+	if err := s.github.CreateOrUpdateFile(ctx, filePath, message, data, existingSHA); err != nil {
+		return nil, fmt.Errorf("upload media: %w", err)
+	}
+
+	return &Item{
+		Name: filename,
+		Path: filePath,
+		URL:  "/uploads/" + filename,
+		Size: len(data),
+	}, nil
+}
+
+func sanitizeFilename(name string) string {
+	name = path.Base(strings.TrimSpace(name))
+	name = strings.ToLower(name)
+	var b strings.Builder
+	for _, r := range name {
+		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '-' || r == '_' || r == '.' {
+			b.WriteRune(r)
+		}
+	}
+	return b.String()
+}
+
+// IsImage returns true if the filename has a common image extension.
+func IsImage(filename string) bool {
+	lower := strings.ToLower(filename)
+	for _, ext := range []string{".png", ".jpg", ".jpeg", ".gif", ".webp", ".svg"} {
+		if strings.HasSuffix(lower, ext) {
+			return true
+		}
+	}
+	return false
+}