Add Idefics3 support (Granite Docling VLM)

Add "idefics3" to VLLM_SUPPORTED_VLM and error message text.
Hook fix merged upstream in unslothai/unsloth-zoo#514.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

unsloth/models/vision.py

@@ -100,6 +100,7 @@ VLLM_SUPPORTED_VLM = [
     "mistral3",
     "qwen3_vl",
     "qwen3_vl_moe",
+    "idefics3",
 ]
 VLLM_NON_LORA_VLM = [
     "mllama",
@@ -459,7 +460,7 @@ class FastBaseModel:
         if is_vlm and fast_inference:
             if not any(arch in VLLM_SUPPORTED_VLM for arch in model_types):
                 raise RuntimeError(
-                    f"Unsloth: Fast inference is only supported for Language models and Qwen2.5-VL, Gemma3 among vision models. "
+                    f"Unsloth: Fast inference is only supported for Language models and Qwen2.5-VL, Gemma3, Idefics3 among vision models. "
                     f"Found architectures: {', '.join(model_types)}!"
                 )