refactor(settings): remove AI Enhancement section and related components

- Deleted AIEnhancementSection and its associated files from the settings view.
- Updated SettingsView to remove references to AI enhancement functionality.
- Cleaned up navigation and feature defaults sections by removing unused validation model references.

This refactor streamlines the settings view by eliminating the AI enhancement feature, which is no longer needed.

apps/ui/src/components/views/settings-view/config/navigation.ts

@@ -8,7 +8,6 @@ import {
   Volume2,
   FlaskConical,
   Trash2,
-  Sparkles,
   Workflow,
   Plug,
   MessageSquareText,
@@ -27,7 +26,6 @@ export const NAV_ITEMS: NavigationItem[] = [
   { id: 'providers', label: 'AI Providers', icon: Bot },
   { id: 'mcp-servers', label: 'MCP Servers', icon: Plug },
   { id: 'prompts', label: 'Prompt Customization', icon: MessageSquareText },
-  { id: 'ai-enhancement', label: 'AI Enhancement', icon: Sparkles },
   { id: 'phase-models', label: 'Phase Models', icon: Workflow },
   { id: 'appearance', label: 'Appearance', icon: Palette },
   { id: 'terminal', label: 'Terminal', icon: SquareTerminal },