#374 feat(desktop): add PostHog feature flag to gate auth requirement

Summary

• Add PostHog feature flag support to desktop app for controlling auth requirement
• require-desktop-auth flag gates whether users must sign in to use the app
• Fix dev/prod singleton lock conflict allowing both to run simultaneously

Changes

• Add posthog-js and create PostHogProvider for feature flag support
• Update CSP to allow PostHog connections (https://*.posthog.com)
• Add app.setName("Superset Dev") in dev mode to prevent singleton lock conflicts
• Centralize feature flags in packages/shared/src/constants.ts

Test plan

• Verify feature flag loads correctly on app start
• Test flag enabled → auth screen shown
• Test flag disabled → no auth required
• Verify dev and prod apps can run simultaneously

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Integrated analytics tracking capability for the desktop application
  • Introduced feature flag system to control app functionality
  • Added configurable authentication requirement for desktop app access
  • Development builds now display as "Superset Dev"

• Chores

  • Added new analytics dependency

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