feat: add AI catalog description generation

docs/install/examples/thothii-installation.local.yaml

@@ -1,4 +1,5 @@
-# Copy this file to an operator-controlled path named exactly thothii-installation.yaml.
+# Copy this file to a protected operator-controlled path named exactly thothii-installation.yaml
+# and set mode 0600 (or 0400) before using it as THT_INSTALLATION_CONFIG_SOURCE.
 # Replace every absolute placeholder. Select exactly one Git transport override.
 profile: local
 projectDirectory: "/absolute/path/to/ThothII"
@@ -7,6 +8,17 @@ workspaceRepository:
   remote: git@git.example.com:organization/workspaces.git
   branch: main
   access: ssh
+metadataGeneration:
+  default: openai-mini
+  models:
+    - id: openai-mini
+      label: OpenAI Mini
+      litellm:
+        provider: openai
+        model: gpt-4.1-mini
+      apiKeyEnv: OPENAI_API_KEY
+    # apiKeyEnv may be omitted only for an explicit endpoint that accepts
+    # unauthenticated requests.
 authentication:
   configDirectory: "/absolute/path/to/thothii-auth"
 overrides: