feat: categories — pages, nav, home block, admin editor select

components/Header.js

@@ -56,6 +56,9 @@ export default function Header() {
           {/* Desktop nav */}
           <nav className="hidden sm:flex items-center gap-1 text-sm">
             <Link href="/" className="btn btn-ghost text-sm py-1.5">Статьи</Link>
+            <Link href="/category/cybersec" className="btn btn-ghost text-sm py-1.5">🔒 Безопасность</Link>
+            <Link href="/category/automation" className="btn btn-ghost text-sm py-1.5">⚡ Автоматизация</Link>
+            <Link href="/category/ai-dev" className="btn btn-ghost text-sm py-1.5">💻 Dev + AI</Link>
             <Link href="/archive" className="btn btn-ghost text-sm py-1.5">Архив</Link>
             <Link href="/notes" className="btn btn-ghost text-sm py-1.5">Заметки</Link>
             <Link href="/about" className="btn btn-ghost text-sm py-1.5">О проекте</Link>

components/admin/ArticleEditor.js

@@ -13,6 +13,7 @@ export default function ArticleEditor({ article }) {
   const [content, setContent] = useState(article?.content || '');
   const [tags, setTags] = useState((article?.tags || []).join(', '));
   const [status, setStatus] = useState(article?.status || 'draft');
+  const [category, setCategory] = useState(article?.category || 'ai-tools');
   const [seoTitle, setSeoTitle] = useState(article?.seo_title || '');
   const [seoDescr, setSeoDescr] = useState(article?.seo_descr || '');
   const [coverUrl, setCoverUrl] = useState(article?.cover_url || '');
@@ -40,6 +41,7 @@ export default function ArticleEditor({ article }) {
         content: content.trim(),
         tags: tags.split(',').map(t => t.trim()).filter(Boolean),
         status,
+        category,
         seo_title: seoTitle.trim() || null,
         seo_descr: seoDescr.trim() || null,
         cover_url: coverUrl.trim() || null,
@@ -268,6 +270,19 @@ export default function ArticleEditor({ article }) {
               <option value="draft">Черновик</option>
               <option value="published">Опубликована</option>
             </select>
+            <div>
+              <label className="block text-xs font-medium text-neutral-500 mb-1">Категория</label>
+              <select
+                value={category}
+                onChange={e => setCategory(e.target.value)}
+                className="w-full px-3 py-2 rounded-lg border border-neutral-200 dark:border-neutral-700 bg-stone-50 dark:bg-neutral-800 text-neutral-900 dark:text-neutral-100 text-sm focus:outline-none focus:ring-2 focus:ring-emerald-500"
+              >
+                <option value="ai-tools">🤖 ИИ-инструменты</option>
+                <option value="cybersec">🔒 Кибербезопасность</option>
+                <option value="automation">⚡ Автоматизация</option>
+                <option value="ai-dev">💻 Разработка с ИИ</option>
+              </select>
+            </div>
             <div>
               <label className="block text-xs font-medium text-neutral-500 mb-1">Теги (через запятую)</label>
               <input