feat(chat): enhance chat interface with markdown support

- Add markdown rendering with react-markdown and remark-gfm
- Create ChatMessage component with code copy functionality
- Add typing indicator animation during AI response
- Create welcome screen for new users
- Add Textarea component for multi-line input
- Improve message styling with avatars and hover actions
- Add Gateway connection status awareness
- Add prose styling for markdown content

src/styles/globals.css

@@ -95,3 +95,66 @@
 .focus-ring {
   @apply focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2;
 }
+
+/* Prose styling for markdown */
+.prose {
+  line-height: 1.6;
+}
+
+.prose p {
+  margin-bottom: 0.75em;
+}
+
+.prose p:last-child {
+  margin-bottom: 0;
+}
+
+.prose ul,
+.prose ol {
+  margin-top: 0.5em;
+  margin-bottom: 0.5em;
+  padding-left: 1.5em;
+}
+
+.prose li {
+  margin-bottom: 0.25em;
+}
+
+.prose pre {
+  margin-top: 0.5em;
+  margin-bottom: 0.5em;
+}
+
+.prose blockquote {
+  border-left: 3px solid hsl(var(--border));
+  padding-left: 1em;
+  margin: 0.5em 0;
+  color: hsl(var(--muted-foreground));
+}
+
+.prose table {
+  width: 100%;
+  border-collapse: collapse;
+  margin: 0.5em 0;
+}
+
+.prose th,
+.prose td {
+  border: 1px solid hsl(var(--border));
+  padding: 0.5em;
+  text-align: left;
+}
+
+.prose th {
+  background: hsl(var(--muted));
+}
+
+/* Typing indicator animation */
+@keyframes bounce {
+  0%, 60%, 100% {
+    transform: translateY(0);
+  }
+  30% {
+    transform: translateY(-4px);
+  }
+}