feat: Kontaktformular als Popup, Grid zentriert, Straße gefixt

- Kontaktformular als Modal-Popup (Name, Organisation, E-Mail, Nachricht)
- Oeffnet per Button-Klick, schliessbar per X/Overlay/Escape
- Submit erstellt mailto-Link mit vorausgefuellten Feldern
- Feature-Grid: letzte 2 Cards zentriert statt linksbuendig
- Gladbacher Strasse -> Gladbacher Straße

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vorschau/js/app.js

@@ -325,6 +325,55 @@ function mdToHtml(md) {
         setTimeout(function () { mapInstance.invalidateSize(); }, 300);
     }
 
+    /* ==================== CONTACT MODAL ==================== */
+    window.openContactModal = function () {
+        document.getElementById('contact-modal').style.display = 'flex';
+        document.body.style.overflow = 'hidden';
+    };
+
+    window.closeContactModal = function () {
+        document.getElementById('contact-modal').style.display = 'none';
+        document.body.style.overflow = '';
+    };
+
+    // Close on overlay click
+    var modalOverlay = document.getElementById('contact-modal');
+    if (modalOverlay) {
+        modalOverlay.addEventListener('click', function (e) {
+            if (e.target === modalOverlay) closeContactModal();
+        });
+    }
+
+    // Close on Escape
+    document.addEventListener('keydown', function (e) {
+        if (e.key === 'Escape' && modalOverlay && modalOverlay.style.display === 'flex') {
+            closeContactModal();
+        }
+    });
+
+    // Form submit -> mailto fallback (no backend yet)
+    window.submitContact = function (e) {
+        e.preventDefault();
+        var name = document.getElementById('cf-name').value;
+        var org = document.getElementById('cf-org').value;
+        var email = document.getElementById('cf-email').value;
+        var msg = document.getElementById('cf-message').value;
+
+        var subject = 'Anfrage von ' + name + (org ? ' (' + org + ')' : '');
+        var body = 'Name: ' + name + '
+Organisation: ' + (org || '-') + '
+E-Mail: ' + email + '
+
+Nachricht:
+' + msg;
+
+        window.location.href = 'mailto:info@aegis-sight.de?subject=' + encodeURIComponent(subject) + '&body=' + encodeURIComponent(body);
+
+        document.getElementById('contact-form').style.display = 'none';
+        document.getElementById('form-success').style.display = 'block';
+        return false;
+    };
+
     /* ==================== INIT ==================== */
     loadLiveData();
 })();