Add new reusable components:
- EmptyState: for empty list/search states with icon, title, description
- ErrorState: for error displays with optional retry button
- LoadingState: for loading states with Spinner and message
- PageHeader: for consistent page headers with title, description, actions
Apply components across pages:
- agents, collections, tool-search pages use new state components
- stats page uses LoadingState and ErrorState
- faq page uses Icon for chevrons
- health page uses Table components
- dashboard agent forms use Input, Select, Textarea, Label
- Replace custom div spinners with Spinner component
f0d271720c