feat(llm): configure GPT-5.6 reasoning defaults

lib/llm/config.rb

@@ -1,7 +1,7 @@
 require 'ruby_llm'
 
 module Llm::Config
-  DEFAULT_MODEL = 'gpt-4.1-mini'.freeze
+  DEFAULT_MODEL = 'gpt-5.6-luna'.freeze
 
   class << self
     def initialized?

lib/llm/feature_router.rb

@@ -1,7 +1,7 @@
 module Llm::FeatureRouter
   class UnknownFeatureError < StandardError; end
 
-  CAPTAIN_V2_ASSISTANT_MODEL = 'gpt-5.2'.freeze
+  CAPTAIN_V2_ASSISTANT_MODEL = 'gpt-5.6-terra'.freeze
 
   class << self
     def resolve(feature:, account: nil)
@@ -17,6 +17,7 @@ module Llm::FeatureRouter
         feature: feature_key,
         provider: Llm::Models.provider_for(model),
         model: model,
+        reasoning_effort: Llm::Models.reasoning_effort_for(feature_key),
         source: source
       }
     end

lib/llm/models.rb

@@ -15,6 +15,10 @@ module Llm::Models
       features.dig(feature.to_s, 'default')
     end
 
+    def reasoning_effort_for(feature)
+      features.dig(feature.to_s, 'reasoning_effort')
+    end
+
     def models_for(feature)
       features.dig(feature.to_s, 'models') || []
     end
@@ -46,7 +50,8 @@ module Llm::Models
             credit_multiplier: model['credit_multiplier']
           }
         end,
-        default: feature['default']
+        default: feature['default'],
+        reasoning_effort: feature['reasoning_effort']
       }
     end
   end

lib/llm_constants.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module LlmConstants
-  DEFAULT_MODEL = 'gpt-4.1'
+  DEFAULT_MODEL = 'gpt-5.6-luna'
   DEFAULT_EMBEDDING_MODEL = 'text-embedding-3-small'
   PDF_PROCESSING_MODEL = 'gpt-4.1-mini'