Remove PostHog analytics and update dependencies to latest minor versions

- Remove posthog-js and posthog-node dependencies
- Delete PostHogProvider component and lib/posthog.ts
- Remove PostHog configuration from environment files
- Remove PostHog rewrites from next.config.mjs
- Update all npm subdependencies to latest minor versions
- Update @types/react and @types/react-dom overrides to 19.2.9 and 19.2.3

docker-compose.override.yml.example

@@ -14,8 +14,6 @@ services:
       - NEXT_PUBLIC_NAVIDROME_URL=http://localhost:4533
       - NEXT_PUBLIC_NAVIDROME_USERNAME=admin
       - NEXT_PUBLIC_NAVIDROME_PASSWORD=admin
-      - NEXT_PUBLIC_POSTHOG_KEY=${POSTHOG_KEY:-}
-      - NEXT_PUBLIC_POSTHOG_HOST=${POSTHOG_HOST:-}
       - PORT=${PORT:-3000}
     
     # Mount source code for development (optional)