feat: enable SSE streaming support in Anthropic handler

- Updated AnthropicHandler to check for streaming configuration before handling SSE transform.
- Modified handleStreaming to use the original request body instead of forcing stream to true.
- Adjusted the transformation logic in AnthropicToBifrost to respect the original stream setting.
- Added logging for SSE streaming configuration in the main application.

handlers/anthropic.go

@@ -140,8 +140,8 @@ func AnthropicHandler(cfg *config.Config, db *gorm.DB) fiber.Handler {
 		targetURL := strings.TrimRight(cfg.OpenAIBackend, "/") + "/v1/chat/completions"
 		logger.Debug("│  🚀 Forwarding to: %s", targetURL)
 
-		// Streaming path: if original request had stream=true, handle SSE transform
-		if isStreamRequest(bodyBytes) {
+		// Streaming path: if enabled and original request had stream=true, handle SSE transform
+		if cfg.Streaming && isStreamRequest(bodyBytes) {
 			return handleStreaming(c, targetURL, reqHeaders, converted, cfg, db, bodyBytes, start)
 		}
 
@@ -269,19 +269,11 @@ func handleStreaming(
 	originalBody []byte,
 	start time.Time,
 ) error {
-	// Enable streaming in the request body
-	var reqMap map[string]interface{}
-	if err := json.Unmarshal(body, &reqMap); err != nil {
-		return c.Status(fiber.StatusInternalServerError).SendString("invalid body")
-	}
-	reqMap["stream"] = true
-	streamBody, _ := json.Marshal(reqMap)
-
 	// Direct HTTP request to upstream (bypass proxy.Forward for streaming)
 	ctx, cancel := context.WithTimeout(c.Context(), time.Duration(cfg.RequestTimeoutSeconds)*time.Second)
 	defer cancel()
 
-	req, err := http.NewRequestWithContext(ctx, "POST", targetURL, bytes.NewReader(streamBody))
+	req, err := http.NewRequestWithContext(ctx, "POST", targetURL, bytes.NewReader(body))
 	if err != nil {
 		return c.Status(fiber.StatusInternalServerError).SendString("build request failed")
 	}