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>

.gitignore

@@ -17,3 +17,7 @@ Thumbs.db
 # Env / secrets (deploy keys, API tokens, etc.)
 .env
 .env.*
+!.env.example
+
+# CMS binary
+/cms/hugo-cms