fix: add thinking parameter to match claude-code request format

converter.go

@@ -14,6 +14,10 @@ func ConvertOpenAIRequest(req *ChatCompletionRequest) *AnthropicRequest {
 		Messages:  convertMessages(remainingMessages),
 		System:    system,
 		MaxTokens: 32000,
+		Thinking: &AnthropicThinking{
+			Type:         "enabled",
+			BudgetTokens: 10000,
+		},
 	}
 
 	if req.MaxTokens != nil {

types.go

@@ -104,6 +104,12 @@ type AnthropicRequest struct {
 	StopSequences []string              `json:"stop_sequences,omitempty"`
 	Tools         []AnthropicTool       `json:"tools,omitempty"`
 	ToolChoice    *AnthropicToolChoice  `json:"tool_choice,omitempty"`
+	Thinking      *AnthropicThinking    `json:"thinking,omitempty"`
+}
+
+type AnthropicThinking struct {
+	Type         string `json:"type"`
+	BudgetTokens int    `json:"budget_tokens,omitempty"`
 }
 
 type AnthropicMessage struct {