## Why

The current setup hardcodes Authentik URLs in the API config and provides only a basic docker-compose.yml without reverse proxy support. For production deployment, the platform needs to integrate with an existing Traefik reverse proxy and have all external service URLs fully configurable via environment variables.

## What Changes

- **Externalize all Authentik and domain configuration** to environment variables (no more hardcoded URLs in config.py).
- **Add `docker-compose.traefik.yml`** for deployment behind an existing Traefik instance with all domain names as env vars.
- **Update `.env.example`** to document all new environment variables for both development and traefik modes.
- **Add proxy web name configuration** for the frontend to know its public URL.
- **Verify OAuth callback URLs work correctly** with configurable domains.

## Capabilities

### New Capabilities
- `traefik-deployment`: Docker Compose setup for deploying behind an existing Traefik reverse proxy with environment-based domain configuration.

### Modified Capabilities
- `docker-infrastructure`: Add traefik deployment mode and externalize all domain/service URLs.
- `auth-oauth`: Make Authentik URLs and callback URLs fully environment-configurable instead of hardcoded.

## Impact

- `apps/api/src/config.py`: Remove hardcoded Authentik URLs, read from environment.
- `apps/api/src/api/auth.py`: Use configurable redirect/callback URLs.
- `.env.example`: Add all new environment variables.
- `docker-compose.traefik.yml`: New file for traefik deployment.
- Frontend may need `VITE_APP_URL` or similar for OAuth redirect.
