feat(agent-view): refactor to folder pattern and add Cursor model support

- Refactor agent-view.tsx from 1028 lines to ~215 lines
- Create agent-view/ folder with components/, hooks/, input-area/, shared/
- Extract hooks: useAgentScroll, useFileAttachments, useAgentShortcuts, useAgentSession
- Extract components: AgentHeader, ChatArea, MessageList, MessageBubble, ThinkingIndicator
- Extract input-area: AgentInputArea, FilePreview, QueueDisplay, InputControls
- Add AgentModelSelector with Claude and Cursor CLI model support
- Update /models/available to use ProviderFactory.getAllAvailableModels()
- Update /models/providers to include Cursor CLI status

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/ui/src/components/views/agent-view/shared/constants.ts

@@ -0,0 +1,9 @@
+// Agent view constants
+
+export const WELCOME_MESSAGE = {
+  id: 'welcome',
+  role: 'assistant' as const,
+  content:
+    "Hello! I'm the Automaker Agent. I can help you build software autonomously. I can read and modify files in this project, run commands, and execute tests. What would you like to create today?",
+  timestamp: new Date().toISOString(),
+};