feat(minecraft): (does it work???)use native reasoning field instead of [REASONING] prefix hack

Replace manual reasoning prefix concatenation with proper reasoning field in Message type, enable reasoning with configurable effort (default: low) in LLM calls, extract reasoningText from response instead of reasoning property

services/minecraft/src/cognitive/conscious/brain.ts

@@ -235,10 +235,13 @@ export class Brain {
 
       // Only append to conversation history after successful parsing (avoid dirty data on retry)
       this.conversationHistory.push({ role: 'user', content: userMessage })
-      const assistantContent = capturedReasoning
-        ? `[REASONING] ${capturedReasoning}\n\n${result}`
-        : result
-      this.conversationHistory.push({ role: 'assistant', content: assistantContent })
+      // Store reasoning in the assistant message's reasoning field (if available)
+      // Reasoning is transient thinking and doesn't need the [REASONING] prefix hack anymore
+      this.conversationHistory.push({
+        role: 'assistant',
+        content: result,
+        ...(capturedReasoning && { reasoning: capturedReasoning }),
+      } as Message)
 
       if (action.tool === 'skip') {
         this.deps.logger.log('INFO', 'Brain: Skipping turn (observing)')

services/minecraft/src/cognitive/conscious/llm-agent.ts

@@ -11,6 +11,7 @@ export interface LLMConfig {
 export interface LLMCallOptions {
     messages: Message[]
     responseFormat?: { type: 'json_object' }
+    reasoning?: { effort: 'low' | 'medium' | 'high' }
 }
 
 export interface LLMResult {
@@ -35,11 +36,13 @@ export class LLMAgent {
             model: this.config.model,
             messages: options.messages,
             ...(options.responseFormat && { responseFormat: options.responseFormat }),
-        })
+            // Enable reasoning with configurable effort (default: low)
+            reasoning: options.reasoning ?? { effort: 'low' },
+        } as Parameters<typeof generateText>[0])
 
         return {
             text: response.text ?? '',
-            reasoning: (response as any).reasoning,
+            reasoning: (response as any).reasoningText,
             usage: response.usage,
         }
     }