feat: read username if email is not available for oauth provider

Also add recipe for OAuth with GitHub setup

recipes/oauth/compose.yml

@@ -0,0 +1,58 @@
+services:
+  backend:
+    image: arcan1s/ahriman:edge
+    privileged: true
+
+    environment:
+      AHRIMAN_DEBUG: yes
+      AHRIMAN_OAUTH_CLIENT_ID: ${AHRIMAN_OAUTH_CLIENT_ID}
+      AHRIMAN_OAUTH_CLIENT_SECRET: ${AHRIMAN_OAUTH_CLIENT_SECRET}
+      AHRIMAN_OUTPUT: console
+      AHRIMAN_PORT: 8080
+      AHRIMAN_PRESETUP_COMMAND: sudo -u ahriman ahriman user-add ${AHRIMAN_OAUTH_USER} -R full -p ""
+      AHRIMAN_REPOSITORY: ahriman-demo
+      AHRIMAN_UNIX_SOCKET: /var/lib/ahriman/ahriman/ahriman.sock
+
+    configs:
+      - source: service
+        target: /etc/ahriman.ini.d/99-settings.ini
+
+    volumes:
+      - type: volume
+        source: repository
+        target: /var/lib/ahriman
+        volume:
+          nocopy: true
+
+    healthcheck:
+      test: curl --fail --silent --output /dev/null http://backend:8080/api/v1/info
+      interval: 10s
+      start_period: 30s
+
+    command: web
+
+  frontend:
+    image: nginx
+    ports:
+      - 8080:80
+
+    configs:
+      - source: nginx
+        target: /etc/nginx/conf.d/default.conf
+
+    volumes:
+      - type: volume
+        source: repository
+        target: /srv
+        read_only: true
+        volume:
+          nocopy: true
+
+configs:
+  nginx:
+    file: nginx.conf
+  service:
+    file: service.ini
+
+volumes:
+  repository: