Improve analytics setup onboarding and dashboard responsiveness

[thebuilder]

Summary

• Add an explicit setup state that directs users to Web Analytics settings when no connections exist
• Enable mock connections only for the example app through configuration
• Improve responsive tabs, breakdown headers, filter actions, flag navigation, and token settings UI
• Expand component and model coverage for onboarding, filtering, and presentation behavior

Testing

• Added and updated Vitest coverage for dashboard setup, filters, breakdown headers, flags, settings, and connection validation
• Not run (not requested)