fix: 明确提示超大 PNG 像素限制

server/utils/image-validation.ts

@@ -0,0 +1,8 @@
+export const MAX_IMAGE_BYTES = 8 * 1024 * 1024
+export const MAX_IMAGE_WIDTH = 10_000
+export const MAX_IMAGE_HEIGHT = 10_000
+export const MAX_IMAGE_PIXELS = 40_000_000
+
+export function isSharpPixelLimitError(error: unknown) {
+  return error instanceof Error && /exceeds pixel limit/i.test(error.message)
+}