Add user auth, personal cabinet, admin panel and first admin bootstrap

Co-authored-by: Cursor <cursoragent@cursor.com>

app/templates/base.html

@@ -21,8 +21,18 @@
                 <span class="logo__text">PhotoHost</span>
             </a>
             <nav class="nav">
-                <a href="#upload" class="nav__link">Загрузить</a>
-                <a href="#gallery" class="nav__link">Галерея</a>
+                <a href="{{ url_for('main.index') }}" class="nav__link">Главная</a>
+                {% if current_user.is_authenticated %}
+                <a href="{{ url_for('cabinet.index') }}" class="nav__link">Личный кабинет</a>
+                {% if current_user.is_admin %}
+                <a href="{{ url_for('admin.dashboard') }}" class="nav__link nav__link--admin">Админка</a>
+                {% endif %}
+                <span class="nav__user">{{ current_user.username }}</span>
+                <a href="{{ url_for('auth.logout') }}" class="nav__link">Выйти</a>
+                {% else %}
+                <a href="{{ url_for('auth.login') }}" class="nav__link">Вход</a>
+                <a href="{{ url_for('auth.register') }}" class="nav__link nav__link--accent">Регистрация</a>
+                {% endif %}
             </nav>
         </div>
     </header>