fix: update dangling references to llama download command (#3763)

## Summary
After removing model management CLI in #3700, this PR updates remaining
references to the old `llama download` command to use `huggingface-cli
download` instead.

## Changes
- Updated error messages in `meta_reference/common.py` to recommend
`huggingface-cli download`
- Updated error messages in
`torchtune/recipes/lora_finetuning_single_device.py` to use
`huggingface-cli download`
- Updated post-training notebook to use `huggingface-cli download`
instead of `llama download`
- Fixed typo: "you model" -> "your model"

## Test Plan
- Verified error messages provide correct guidance for users
- Checked that notebook instructions are up-to-date with current tooling

llama_stack/providers/inline/inference/meta_reference/common.py

@@ -18,7 +18,7 @@ def model_checkpoint_dir(model_id) -> str:
 
     assert checkpoint_dir.exists(), (
         f"Could not find checkpoints in: {model_local_dir(model_id)}. "
-        f"If you try to use the native llama model, Please download model using `llama download --model-id {model_id}`"
-        f"Otherwise, please save you model checkpoint under {model_local_dir(model_id)}"
+        f"If you try to use the native llama model, please download the model using `llama-model download --source meta --model-id {model_id}` (see https://github.com/meta-llama/llama-models). "
+        f"Otherwise, please save your model checkpoint under {model_local_dir(model_id)}"
     )
     return str(checkpoint_dir)

llama_stack/providers/inline/post_training/torchtune/recipes/lora_finetuning_single_device.py

@@ -104,9 +104,10 @@ class LoraFinetuningSingleDevice:
             if not any(p.exists() for p in paths):
                 checkpoint_dir = checkpoint_dir / "original"
 
+            hf_repo = model.huggingface_repo or f"meta-llama/{model.descriptor()}"
             assert checkpoint_dir.exists(), (
                 f"Could not find checkpoints in: {model_local_dir(model.descriptor())}. "
-                f"Please download model using `llama download --model-id {model.descriptor()}`"
+                f"Please download the model using `huggingface-cli download {hf_repo} --local-dir ~/.llama/{model.descriptor()}`"
             )
             return str(checkpoint_dir)