docs: sync oauth-traefik-integration specs to main specs

- Update auth-oauth spec: configurable endpoints via environment variables
- Update docker-infrastructure spec: add traefik deployment mode
- Add traefik-deployment spec: new capability for reverse proxy deployment

openspec/specs/traefik-deployment/spec.md

@@ -0,0 +1,31 @@
+## ADDED Requirements
+
+### Requirement: Traefik Docker Compose
+
+The system SHALL provide a `docker-compose.traefik.yml` for deployment behind an existing Traefik reverse proxy.
+
+#### Scenario: Service labels
+- GIVEN the traefik deployment configuration
+- WHEN services are started
+- THEN `docker-compose.traefik.yml` SHALL define Traefik Docker labels for each service
+- AND all routing rules SHALL use configurable domain names
+
+#### Scenario: Environment variables
+- GIVEN the traefik deployment configuration
+- WHEN configuring the deployment
+- THEN all domain names SHALL be configurable via environment variables
+- AND the proxy web name SHALL be configurable via environment variable
+
+### Requirement: Environment Configuration
+
+The system SHALL document all required environment variables for traefik deployment.
+
+#### Scenario: Required variables
+- GIVEN a new deployment
+- WHEN setting up environment variables
+- THEN `.env.example` SHALL document:
+  - `API_DOMAIN` - domain for API service
+  - `WEB_DOMAIN` - domain for web frontend
+  - `AUTHENTIK_DOMAIN` - domain for Authentik instance
+  - `PROXY_WEB_NAME` - name for web proxy service
+  - All Authentik OIDC configuration variables