feat(ui): add toast notifications and more polish

- Add toast notification system with slide-in animation
- Toast types: info, success, warning, error
- Show connection status toasts on connect/disconnect
- Add toast container styling with proper z-index

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/web/public/styles.css

@@ -868,6 +868,57 @@ body {
   color: var(--green);
 }
 
+/* Toast notifications */
+.toast-container {
+  position: fixed;
+  top: 1rem;
+  right: 1rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+  z-index: 10000;
+  pointer-events: none;
+}
+
+.toast {
+  background: linear-gradient(135deg, #2a2a2a 0%, #1a1a1a 100%);
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  padding: 0.875rem 1.25rem;
+  font-size: 0.875rem;
+  color: var(--text);
+  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
+  transform: translateX(100%);
+  opacity: 0;
+  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
+  pointer-events: auto;
+}
+
+.toast.show {
+  transform: translateX(0);
+  opacity: 1;
+}
+
+.toast-success {
+  border-color: rgba(34, 197, 94, 0.4);
+  background: linear-gradient(135deg, rgba(34, 197, 94, 0.2) 0%, rgba(34, 197, 94, 0.1) 100%);
+}
+
+.toast-error {
+  border-color: rgba(239, 68, 68, 0.4);
+  background: linear-gradient(135deg, rgba(239, 68, 68, 0.2) 0%, rgba(239, 68, 68, 0.1) 100%);
+}
+
+.toast-warning {
+  border-color: rgba(234, 179, 8, 0.4);
+  background: linear-gradient(135deg, rgba(234, 179, 8, 0.2) 0%, rgba(234, 179, 8, 0.1) 100%);
+}
+
+.toast-info {
+  border-color: rgba(59, 130, 246, 0.4);
+  background: linear-gradient(135deg, rgba(59, 130, 246, 0.2) 0%, rgba(59, 130, 246, 0.1) 100%);
+}
+
 /* Tabs */
 .tabs {
   display: flex;