Added claudflare Turnstile captcha support

templates/landing.html

@@ -50,6 +50,10 @@
     }
     </script>
 
+    {% if !turnstile_site_key.is_empty() %}
+    <script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>
+    {% endif %}
+
     <style>
         /* ── Reset & Base ── */
         *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
@@ -464,6 +468,9 @@
                 <input type="checkbox" id="consent" name="consent" required style="margin-top:0.2rem;width:auto;flex-shrink:0;">
                 <label for="consent" style="font-size:0.82rem;font-weight:400;color:#7a7599;cursor:pointer;display:inline;">{{ t.landing_form_consent }}</label>
             </div>
+            {% if !turnstile_site_key.is_empty() %}
+            <div class="cf-turnstile" data-sitekey="{{ turnstile_site_key }}" data-theme="light" style="margin-bottom:1.25rem;"></div>
+            {% endif %}
             <button type="submit" class="form-submit">{{ t.landing_form_submit }}</button>
         </form>
         {% if !contact_info.is_empty() %}