feat: add chat page layout with message list and bubble components

- Create /chat route with scrollable message list
- MessageBubble component with distinct user/assistant styles
- MessageList with auto-scroll-to-bottom on new messages
- Empty state display when no messages
- ChatMessage type definition in src/lib/types.ts
- Add browser globals to ESLint config for Svelte files

Closes #5

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/routes/chat/+page.svelte

@@ -0,0 +1,14 @@
+<script lang="ts">
+	import type { ChatMessage } from '$lib/types';
+	import MessageList from '$lib/components/MessageList.svelte';
+
+	let messages: ChatMessage[] = $state([]);
+</script>
+
+<div class="flex h-screen flex-col">
+	<header class="border-b border-gray-200 bg-white px-4 py-3">
+		<h1 class="text-lg font-semibold text-gray-900">Chat</h1>
+	</header>
+
+	<MessageList {messages} />
+</div>