fix: correct model paths in SD3.5 and SDXL Refiner workflows

Changed from diffusers paths to actual .safetensors filenames:
- sd3.5: diffusers/stable-diffusion-3.5-large -> sd3.5_large.safetensors
- sdxl-base: diffusers/stable-diffusion-xl-base-1.0 -> sd_xl_base_1.0.safetensors
- sdxl-refiner: diffusers/stable-diffusion-xl-refiner-1.0 -> sd_xl_refiner_1.0.safetensors

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

comfyui/workflows/text-to-image/sd35-large-t2i-production-v1.json

@@ -33,7 +33,7 @@
       "properties": {
         "Node name for S&R": "CheckpointLoaderSimple"
       },
-      "widgets_values": ["diffusers/stable-diffusion-3.5-large"],
+      "widgets_values": ["sd3.5_large.safetensors"],
       "title": "SD3.5 Large Checkpoint Loader"
     },
     {

comfyui/workflows/text-to-image/sdxl-refiner-t2i-production-v1.json

@@ -33,7 +33,7 @@
       "properties": {
         "Node name for S&R": "CheckpointLoaderSimple"
       },
-      "widgets_values": ["diffusers/stable-diffusion-xl-base-1.0"],
+      "widgets_values": ["sd_xl_base_1.0.safetensors"],
       "title": "SDXL Base Checkpoint Loader"
     },
     {
@@ -67,7 +67,7 @@
       "properties": {
         "Node name for S&R": "CheckpointLoaderSimple"
       },
-      "widgets_values": ["diffusers/stable-diffusion-xl-refiner-1.0"],
+      "widgets_values": ["sd_xl_refiner_1.0.safetensors"],
       "title": "SDXL Refiner Checkpoint Loader"
     },
     {