feat(webhooks): add simple frontend webhook configuration UI (Phase 4)

client/src/App.css

@@ -304,3 +304,158 @@ body {
     grid-template-columns: 1fr;
   }
 }
+
+/* Webhooks Section Styles */
+.webhooks-section {
+  background: white;
+  border-radius: 10px;
+  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
+  margin-bottom: 20px;
+  overflow: hidden;
+}
+
+.webhooks-header {
+  padding: 20px 30px;
+  background: #f8f9fa;
+  border-bottom: 2px solid #e0e0e0;
+  cursor: pointer;
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  transition: background 0.3s;
+}
+
+.webhooks-header:hover {
+  background: #f0f1f2;
+}
+
+.webhooks-header h2 {
+  color: #333;
+  font-size: 1.3rem;
+  margin: 0;
+}
+
+.webhooks-toggle {
+  font-size: 1.2rem;
+  color: #666;
+  transition: transform 0.3s;
+}
+
+.webhooks-toggle.expanded {
+  transform: rotate(180deg);
+}
+
+.webhooks-content {
+  padding: 20px 30px;
+}
+
+.webhook-instance {
+  padding: 20px 0;
+  border-bottom: 1px solid #e0e0e0;
+}
+
+.webhook-instance:last-child {
+  border-bottom: none;
+}
+
+.webhook-instance h3 {
+  color: #333;
+  font-size: 1.1rem;
+  margin-bottom: 15px;
+}
+
+.webhook-status {
+  display: flex;
+  align-items: center;
+  gap: 15px;
+  margin-bottom: 15px;
+}
+
+.status-indicator {
+  font-size: 1rem;
+  font-weight: 500;
+  padding: 5px 15px;
+  border-radius: 20px;
+}
+
+.status-indicator.enabled {
+  background: #e8f5e9;
+  color: #4caf50;
+}
+
+.status-indicator.disabled {
+  background: #f5f5f5;
+  color: #999;
+}
+
+.enable-webhook-btn {
+  padding: 8px 16px;
+  background: #667eea;
+  color: white;
+  border: none;
+  border-radius: 5px;
+  cursor: pointer;
+  font-size: 0.95rem;
+  transition: background 0.3s;
+}
+
+.enable-webhook-btn:hover {
+  background: #5568d3;
+}
+
+.enable-webhook-btn:disabled {
+  background: #ccc;
+  cursor: not-allowed;
+}
+
+.test-webhook-btn {
+  padding: 8px 16px;
+  background: #f093fb;
+  color: white;
+  border: none;
+  border-radius: 5px;
+  cursor: pointer;
+  font-size: 0.95rem;
+  transition: background 0.3s;
+}
+
+.test-webhook-btn:hover {
+  background: #d97ed8;
+}
+
+.test-webhook-btn:disabled {
+  background: #ccc;
+  cursor: not-allowed;
+}
+
+.webhook-triggers {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
+  gap: 10px;
+  padding-top: 15px;
+  border-top: 1px solid #e0e0e0;
+}
+
+.trigger-item {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.trigger-label {
+  color: #666;
+  font-size: 0.9rem;
+}
+
+.trigger-value {
+  font-weight: 500;
+  font-size: 1.1rem;
+}
+
+.trigger-value.active {
+  color: #4caf50;
+}
+
+.trigger-value.inactive {
+  color: #999;
+}