Remove all database dependencies and simplify application

BREAKING CHANGE: Remove all data analysis features

This commit removes all database-dependent functionality and simplifies
the application to focus on authentication and user management only.

Changes:
- Remove all /api/data and /api/metadata server endpoints
- Remove Supabase configuration from nuxt.config.ts and .env.example
- Remove @supabase/supabase-js dependency from package.json
- Delete data analysis pages: explorer, metadatos, rawExplorer, panorama,
  comparativa-cosechas, informe-ingresos
- Simplify sidebar navigation to show only "Inicio"
- Update home page to focus on authentication and profile management
- Remove "Supabase" and "Solo lectura" badges from navbar
- Keep only auth-related API endpoints: /api/auth/status and /api/auth/check-group

The application now serves as an authentication-protected portal with:
- Authentik SSO integration
- User profile management
- Settings and notifications pages (coming soon)
- No database or data analysis features

nuxt4-app/package.json

@@ -14,7 +14,6 @@
     "@nuxt/test-utils": "^3.19.2",
     "@nuxt/ui": "^4.0.0",
     "@pinia/nuxt": "^0.11.2",
-    "@supabase/supabase-js": "^2.48.0",
     "@vite-pwa/nuxt": "^0.9.1",
     "nuxt": "^4.1.2",
     "pinia": "^3.0.3",