Add CyberMail Email Delivery integration

- New emailDelivery Django app with full platform API integration
- Account connection, domain management, SMTP credentials, relay config
- Auto-configure SPF/DKIM/DMARC DNS records via PowerDNS
- Postfix SMTP relay through CyberMail (configureRelayHost/removeRelayHost)
- Real-time delivery logs, stats, and per-domain analytics
- Single-page AngularJS dashboard with marketing landing page
- Promotional banners on 6 email-related pages with dismiss cookie
- Manual SQL table creation in upgrade.py for existing installs
- Documentation: setup guide, technical reference, user guide

webmail/templates/webmail/index.html

@@ -8,6 +8,21 @@
 
 <div class="webmail-container" ng-controller="webmailCtrl" ng-init="init()">
 
+    <div id="cybermailBanner" style="display:none;flex-shrink:0;">
+      <div style="padding:10px 20px;display:flex;align-items:center;gap:14px;background:linear-gradient(135deg,#4f46e5 0%,#7c3aed 50%,#9333ea 100%);">
+        <div style="flex-shrink:0;font-size:22px;">&#9993;</div>
+        <div style="flex:1;min-width:0;font-size:12.5px;color:rgba(255,255,255,0.85);">
+          <span style="color:#fff;font-weight:800;font-size:13.5px;">Stop Landing in Spam</span> &mdash; Route emails through CyberMail. <strong style="color:#fff;">15,000 emails/month free.</strong> <a href="https://cyberpanel.net/KnowledgeBase/cybermail-user-guide/" target="_blank" style="color:rgba(255,255,255,0.9);text-decoration:underline;">Learn more</a>
+        </div>
+        <a href="/emailDelivery/" style="background:#fff;color:#4f46e5;padding:6px 18px;border-radius:5px;font-weight:700;font-size:11.5px;text-decoration:none;white-space:nowrap;flex-shrink:0;">Get Started Free &rarr;</a>
+        <button onclick="dismissCyberMailBanner()" style="background:none;border:none;color:rgba(255,255,255,0.5);font-size:18px;cursor:pointer;padding:0 2px;line-height:1;flex-shrink:0;" title="Dismiss">&times;</button>
+      </div>
+    </div>
+    <script>
+    (function(){if(!document.cookie.includes('cybermail_dismiss=1')){document.getElementById('cybermailBanner').style.display='';}})();
+    function dismissCyberMailBanner(){document.getElementById('cybermailBanner').style.display='none';document.cookie='cybermail_dismiss=1; path=/; max-age='+7*86400;}
+    </script>
+
     <!-- Account Switcher Bar -->
     <div class="wm-account-bar" ng-show="managedAccounts.length > 1">
         <div class="wm-account-current">