Connect Ulysses to searxng network for search engine access

searxng runs on a separate Docker network (searxng_default) and the
container couldn't reach host-port 8888 due to Docker bridge isolation.
Added searxng_default as external network and attached odysseus service
to it, allowing direct container-to-container communication via
http://searxng:8080.

docker-compose.yml

@@ -29,7 +29,7 @@ services:
       - RESEARCH_LLM_ENDPOINT=${RESEARCH_LLM_ENDPOINT:-}
       - HF_TOKEN=${HF_TOKEN:-}
       - HUGGING_FACE_HUB_TOKEN=${HUGGING_FACE_HUB_TOKEN:-}
-      - SEARXNG_INSTANCE=http://host.docker.internal:8888
+      - SEARXNG_INSTANCE=http://searxng:8080
       - CHROMADB_HOST=chromadb
       - CHROMADB_PORT=8000
       - DATABASE_URL=${DATABASE_URL:-sqlite:///./data/app.db}
@@ -77,6 +77,9 @@ services:
       chromadb:
         condition: service_started
     restart: unless-stopped
+    networks:
+      - default
+      - searxng-net
 
   chromadb:
     image: docker.io/chromadb/chroma:latest
@@ -153,3 +156,8 @@ volumes:
 #  searxng-data:
   chromadb-data:
   ntfy-cache:
+
+networks:
+  searxng-net:
+    external: true
+    name: searxng_default