Added claudflare Turnstile captcha support

templates/admin/login.html

@@ -6,6 +6,9 @@
     <title>{{ t.nav_title }} — {{ t.login_title }}</title>
     <link rel="icon" type="image/svg+xml" href="/favicon.svg">
     <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@1/css/bulma.min.css">
+    {% if !turnstile_site_key.is_empty() %}
+    <script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>
+    {% endif %}
     <style>
         :root { color-scheme: light; }
         body { background: #f5f5f5; display: flex; align-items: center; justify-content: center; min-height: 100vh; color: #333; }
@@ -41,6 +44,9 @@
                     <label class="label">{{ t.users_password }}</label>
                     <div class="control"><input class="input" type="password" name="password" required></div>
                 </div>
+                {% if !turnstile_site_key.is_empty() %}
+                <div class="cf-turnstile" data-sitekey="{{ turnstile_site_key }}" data-theme="light" style="margin-top:0.75rem;"></div>
+                {% endif %}
                 <button type="submit" class="button is-primary is-fullwidth mt-3">{{ t.login_button }}</button>
             </form>
         </div>