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

build_process/process.md

@@ -13,6 +13,7 @@
 * [commit_5] Channel connection flows - Multi-channel support with QR/token connection UI
 * [commit_6] Auto-update functionality - electron-updater integration with UI
 * [commit_7] Packaging and distribution - CI/CD, multi-platform builds, icon generation
+* [commit_8] Chat interface - Markdown support, typing indicator, welcome screen
 
 ### Plan:
 1. ~~Initialize project structure~~ ✅
@@ -22,7 +23,7 @@
 5. ~~Implement Channel connection flows~~ ✅
 6. ~~Add auto-update functionality~~ ✅
 7. ~~Packaging and distribution setup~~ ✅
-8. Chat interface
+8. ~~Chat interface~~ ✅
 9. Skills browser/enable page
 10. Cron tasks management