fix(config): use docker hostnames for tatlock and searxng defaults

The homelab is retiring *.schweitz.internal and will rebind host ports
to 127.0.0.1, so container-to-container traffic must use container
names on the docker-dataplane network. Switch defaults from host
IP:port to http://tatlock:8000 and http://searxng:8080 (SearXNG's
internal port is 8080; 8087 is only the host-published port).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

webber-api/tests/test_web_search.py

@@ -12,7 +12,7 @@ class TestWebSearchTool:
 
     @pytest.fixture
     def tool(self):
-        return WebSearchTool(searxng_url="http://localhost:8087", timeout=5)
+        return WebSearchTool(searxng_url="http://searxng:8080", timeout=5)
 
     @pytest.fixture
     def mock_search_response(self):