[Enhancement] Studio UI refresh and documentation

[zephyrzilla]

Summary

Major UI refresh for SyGra Studio with a comprehensive design system overhaul, improved documentation, and legacy UI/script cleanup. This PR modernizes the visual appearance, enhances user experience across all views, and provides detailed step-by-step documentation for using the SyGra Studio interface.

How to Test

Test the UI refresh:

1. Start Studio: make studio
2. Navigate to http://localhost:8000
3. Verify the refreshed UI across all views:
   • Home dashboard with stats
   • Workflows list
   • Models view
   • Runs history with filters
   • Library (recipes + tools)
4. Create a workflow and verify node styling
5. Run a workflow and check execution panel

Test documentation:

1. Run make docs-serve
2. Navigate to "Getting Started" -> "SyGra Studio"
3. Verify all sections render correctly with tables and code blocks

Verify cleanup:

1. Confirm apps/ directory no longer exists
2. Confirm run_ui.sh no longer exists
3. Run make test to ensure no broken imports

Checklist

• Lint fixes and unit testing done
• End to end task testing
• Documentation updated