added header and footer

Co-authored-by: Copilot <copilot@github.com>

src/app/site-header/site-header.html

@@ -0,0 +1,46 @@
+<header class="site-header">
+  <div class="site-header__inner">
+
+    <!-- Brand -->
+    <a class="site-header__brand" routerLink="/" (click)="closeMenu()">
+      <img src="/logo_small.png" alt="fastCHECK" width="32" height="32" />
+      <span class="site-header__wordmark">
+        <span class="wm-fast">fast</span><span class="wm-check">CHECK</span>
+      </span>
+    </a>
+
+    <!-- Desktop nav -->
+    <nav class="site-header__nav" aria-label="Навигация">
+      <a class="site-header__link" href="#about">О сервисе</a>
+      <a class="site-header__link" href="#contacts">Контакты</a>
+      <a class="site-header__link" href="mailto:info@viaexport.store">Поддержка</a>
+    </nav>
+
+    <!-- Mobile hamburger -->
+    <button class="site-header__burger" type="button"
+            [attr.aria-expanded]="menuOpen()"
+            aria-label="Меню"
+            (click)="toggleMenu()">
+      @if (menuOpen()) {
+        <svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor"
+             stroke-width="2.5" stroke-linecap="round">
+          <line x1="18" y1="6" x2="6" y2="18"/><line x1="6" y1="6" x2="18" y2="18"/>
+        </svg>
+      } @else {
+        <svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor"
+             stroke-width="2.5" stroke-linecap="round">
+          <line x1="3" y1="7" x2="21" y2="7"/><line x1="3" y1="12" x2="21" y2="12"/><line x1="3" y1="17" x2="21" y2="17"/>
+        </svg>
+      }
+    </button>
+  </div>
+
+  <!-- Mobile dropdown -->
+  @if (menuOpen()) {
+    <nav class="site-header__mobile-menu" (click)="closeMenu()" aria-label="Мобильное меню">
+      <a class="site-header__mobile-link" href="#about">О сервисе</a>
+      <a class="site-header__mobile-link" href="#contacts">Контакты</a>
+      <a class="site-header__mobile-link" href="mailto:info@viaexport.store">Поддержка</a>
+    </nav>
+  }
+</header>