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>

package.json

@@ -28,6 +28,7 @@
 		"eslint": "^9.0.0",
 		"eslint-config-prettier": "^10.0.0",
 		"eslint-plugin-svelte": "^3.0.0",
+		"globals": "^17.4.0",
 		"prettier": "^3.0.0",
 		"prettier-plugin-svelte": "^3.0.0",
 		"svelte": "^5.51.0",