added support for the new Flux image gen model using ComfyUI

this commit adds three environment variables:

- COMFYUI_FLUX: determines whether Flux is used, the workflow is completely different so this is necessary.
- COMFYUI_FLUX_WEIGHT_DTYPE: sets the weight precision for Flux. you will probably want to set this to "fp8_e4m3fn" as the fp16 weights take up about 24GB of VRAM. optional, defaults to "default".
- COMFYUI_FLUX_FP8_CLIP: Flux requires two CLIP models downloaded, one of which is available in fp8 and fp16. set to true if you are using the fp8 CLIP weights.

backend/config.py

@@ -1302,6 +1302,24 @@ COMFYUI_SD3 = PersistentConfig(
     os.environ.get("COMFYUI_SD3", "").lower() == "true",
 )
 
+COMFYUI_FLUX = PersistentConfig(
+    "COMFYUI_FLUX",
+    "image_generation.comfyui.flux",
+    os.environ.get("COMFYUI_FLUX", "").lower() == "true",
+)
+
+COMFYUI_FLUX_WEIGHT_DTYPE = PersistentConfig(
+    "COMFYUI_FLUX_WEIGHT_DTYPE",
+    "image_generation.comfyui.flux_weight_dtype",
+    os.getenv("COMFYUI_FLUX_WEIGHT_DTYPE", ""),
+)
+
+COMFYUI_FLUX_FP8_CLIP = PersistentConfig(
+    "COMFYUI_FLUX_FP8_CLIP",
+    "image_generation.comfyui.flux_fp8_clip",
+    os.getenv("COMFYUI_FLUX_FP8_CLIP", ""),
+)
+
 IMAGES_OPENAI_API_BASE_URL = PersistentConfig(
     "IMAGES_OPENAI_API_BASE_URL",
     "image_generation.openai.api_base_url",