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/static/js/media.js

@@ -0,0 +1,48 @@
+(function () {
+  'use strict';
+
+  const form = document.getElementById('media-upload-form');
+  const status = document.getElementById('upload-status');
+
+  if (form) {
+    form.addEventListener('submit', async function (e) {
+      e.preventDefault();
+      const fileInput = document.getElementById('media-file');
+      if (!fileInput.files[0]) return;
+
+      const formData = new FormData();
+      formData.append('file', fileInput.files[0]);
+
+      status.textContent = 'Uploading…';
+      status.className = 'save-status saving';
+
+      try {
+        const res = await fetch('/api/media/upload', {
+          method: 'POST',
+          body: formData,
+        });
+        const result = await res.json();
+        if (!res.ok) throw new Error(result.error || 'Upload failed');
+
+        status.textContent = 'Uploaded!';
+        status.className = 'save-status saved';
+        fileInput.value = '';
+        setTimeout(function () { window.location.reload(); }, 800);
+      } catch (err) {
+        status.textContent = err.message;
+        status.className = 'save-status error';
+      }
+    });
+  }
+
+  document.querySelectorAll('.copy-md').forEach(function (btn) {
+    btn.addEventListener('click', function () {
+      const url = btn.getAttribute('data-url');
+      const md = '![](' + url + ')';
+      navigator.clipboard.writeText(md).then(function () {
+        btn.textContent = 'Copied!';
+        setTimeout(function () { btn.textContent = 'Copy Markdown'; }, 1500);
+      });
+    });
+  });
+})();