Add posthog

[vcarl]

• needs new secrets configured before ready to merge

[what-the-diff]

PR Summary

• Added PostHog Keys
  Introduced keys for PostHog, a user behavior analytics tool, in the .env.example file. The added keys are VITE_PUBLIC_POSTHOG_KEY and VITE_PUBLIC_POSTHOG_HOST.

• Secrets for PostHog in GitHub Actions
  Updated the GitHub Actions workflow file (node.js.yml) to include secrets for the same PostHog variables, ensuring secure implementation of user analytics.

• Integrated Analytics in Application Component
  Updated entry.client.tsx file to integrate the PostHogProvider, the provider component from the PostHog JavaScript library, for tracking user behaviors in our application.

• Incorporated PostHog keys in Deployment
  Made changes to deployment.yaml (Kubernetes deployment file) to include the PostHog environment variables, ensuring the user behavior analytics functionality is available upon deployment.

• Updated Package Lists and Added PostHog JavaScript Library
  The package-lock.json and package.json files were updated to include the PostHog JavaScript library (posthog-js) version 1.280.1. This library provides the functionalities required for tracking user behavior analytics in the application.