Add project scaffolding and documentation

Add .env.example with configuration for database, Redis, security, SMTP, workers, and plugins. Add .gitignore for Python, Node.js, Next.js, Docker volumes, and IDE files. Add MIT License. Update README.md with feature overview, quick start guide, architecture description, plugin system documentation, security details, backup/restore instructions, and developer setup. Add Alembic configuration files and placeholder directories for API, web, worker, and plugin components

docs/admin/README.md

@@ -0,0 +1,56 @@
+# NexaDash Admin Guide
+
+## Initial Setup
+
+After starting the Docker Compose stack, open the web UI and create the owner account. The setup wizard is only available while no user exists.
+
+## User Management
+
+- Roles: Owner, Admin, Editor, Viewer.
+- Invite users via email or create them directly.
+- Users can change their own password and profile settings.
+
+## Plugin Management
+
+1. Install built-in plugins automatically from the plugin registry.
+2. Upload custom plugins as ZIP files.
+3. Activate/deactivate plugins per environment.
+4. Configure service connections for each plugin.
+
+## Service Connections
+
+Each plugin instance needs a service connection with:
+
+- Base URL
+- TLS verification option
+- Encrypted credentials
+- Timeout
+
+Always test the connection before saving.
+
+## Dashboards
+
+- Create dashboards per user or team.
+- Use the editor to drag, drop and resize widgets.
+- Save layouts per breakpoint.
+- Set auto-refresh intervals.
+
+## Monitoring
+
+- View audit logs for security-relevant actions.
+- Check plugin health and logs.
+- Monitor background job status.
+
+## Mail Settings
+
+Configure SMTP in the UI to send invitation and password reset emails.
+
+## Backup
+
+Use the database dump command documented in `docs/deployment/README.md` or automate it with a cron job.
+
+## Troubleshooting
+
+- Check API logs: `docker compose logs api`
+- Check worker logs: `docker compose logs worker`
+- Check plugin logs in the UI or database.