fix: Clarifies AI model name description

Updates the AI model name description to indicate that the model is automatically detected from available models.

Sets the default value for the model to an empty string, reflecting the auto-detection behavior.

Author: KariHall619

cmd/testdata/stores.yaml

@@ -18,8 +18,8 @@ stores:
           description: "AI provider (local, openai, claude)"
           defaultValue: "local"
         - key: "model"
-          description: "AI model name"
-          defaultValue: "codellama"
+          description: "AI model name (auto-detected from available models)"
+          defaultValue: ""
         - key: "endpoint"
           description: "AI service endpoint"
           defaultValue: "http://localhost:11434"