fix(worker): 限制大图归一化峰值内存

6K 多参考图在 P24 下会并发进入高内存缩放并击穿 2 GiB Worker。新增独立可配置的图片归一化并发，生产默认 2，只约束解码、缩放和重编码阶段，不占用视频上游等待槽；缩放器改为内存稳定的近似双线性实现。\n\n验证：6K 到 6000x2400 转换、信号量串行化、Go 全量测试、gofmt、Kubernetes 客户端 dry-run。

apps/api/internal/runner/input_image_normalizer_test.go

@@ -10,6 +10,7 @@ import (
 	"image/png"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/easyai/easyai-ai-gateway/apps/api/internal/clients"
 	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
@@ -61,6 +62,15 @@ func decodedImageSize(t *testing.T, source string) image.Point {
 	return image.Pt(config.Width, config.Height)
 }
 
+func jpegImageDataURL(t *testing.T, width int, height int) string {
+	t.Helper()
+	var payload bytes.Buffer
+	if err := jpeg.Encode(&payload, image.NewRGBA(image.Rect(0, 0, width, height)), &jpeg.Options{Quality: 90}); err != nil {
+		t.Fatal(err)
+	}
+	return "data:image/jpeg;base64," + base64.StdEncoding.EncodeToString(payload.Bytes())
+}
+
 func TestNormalizeVideoInputImagesResizesOversizedSeedanceImage(t *testing.T) {
 	service := &Service{}
 	body := map[string]any{
@@ -85,6 +95,58 @@ func TestNormalizeVideoInputImagesResizesOversizedSeedanceImage(t *testing.T) {
 	}
 }
 
+func TestNormalizeVideoInputImagesBoundsSixKReferenceMemoryWork(t *testing.T) {
+	service := &Service{imageNormalizeSlots: make(chan struct{}, 1)}
+	candidate := store.RuntimeModelCandidate{
+		ModelType: "omni_video",
+		Capabilities: map[string]any{
+			"omni_video": map[string]any{
+				"input_image_resolution_range": map[string]any{
+					"min": map[string]any{"long_edge": float64(300), "short_edge": float64(300)},
+					"max": map[string]any{"long_edge": float64(6000), "short_edge": float64(6000)},
+				},
+				"input_image_aspect_ratio_range": []any{float64(0.4), float64(2.5)},
+			},
+		},
+	}
+	body := map[string]any{"first_frame": jpegImageDataURL(t, 6144, 2160)}
+	normalized, err := service.normalizeVideoInputImages(context.Background(), body, candidate)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := decodedImageSize(t, normalized["first_frame"].(string)); got != image.Pt(6000, 2400) {
+		t.Fatalf("unexpected converted size: %v", got)
+	}
+}
+
+func TestImageNormalizationSlotSerializesHeavyConversions(t *testing.T) {
+	service := &Service{imageNormalizeSlots: make(chan struct{}, 1)}
+	releaseFirst, err := service.acquireImageNormalizationSlot(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	acquired := make(chan func(), 1)
+	go func() {
+		release, acquireErr := service.acquireImageNormalizationSlot(context.Background())
+		if acquireErr == nil {
+			acquired <- release
+		}
+	}()
+	select {
+	case release := <-acquired:
+		release()
+		t.Fatal("second normalization entered while the only slot was held")
+	case <-time.After(50 * time.Millisecond):
+	}
+	releaseFirst()
+	select {
+	case release := <-acquired:
+		release()
+	case <-time.After(time.Second):
+		t.Fatal("second normalization did not acquire the released slot")
+	}
+}
+
 func TestNormalizeVideoInputImagesPadsAspectRatioViolation(t *testing.T) {
 	service := &Service{}
 	source := pngImageDataURL(t, 1530, 500)