feat: add ESSENTIALS_CATEGORY to core nodes

Marked nodes:
- Basic: LoadImage, SaveImage, LoadVideo, SaveVideo, Load3D, CLIPTextEncode
- Image Tools: ImageScale, ImageInvert, ImageBatch, ImageCrop, ImageRotate, ImageBlur
- Image Tools/Preprocessing: Canny
- Image Generation: LoraLoader
- Audio: LoadAudio, SaveAudio

Amp-Thread-ID: https://ampcode.com/threads/T-019c2b25-cd90-7218-9071-03cb46b351b3

comfy_extras/nodes_post_processing.py

@@ -77,6 +77,7 @@ class Blur(io.ComfyNode):
         return io.Schema(
             node_id="ImageBlur",
             category="image/postprocessing",
+            essentials_category="Image Tools",
             inputs=[
                 io.Image.Input("image"),
                 io.Int.Input("blur_radius", default=1, min=1, max=31, step=1),