Cannot upload local file for submit_py_files in V3

**PySDK Version**

- [ ] PySDK V2 (2.x)
- [x] PySDK V3 (3.x)

**Describe the bug**

The PySparkProcessor `run` no longer accepts local files due to the change to `ProcessingInput` interface - e.g. regression introduced in 3203e49

**To reproduce**

Insert a local file path into the list passed as `submit_py_files` in `sagemaker.core.spark.processing.PySparkProcessor.run()`.

(Let me know if you need a more concrete example).

**Expected behavior**

Successfully starts the job.

**Screenshots or logs**

PyDantic reports the following errors:

```
ValidationError: 2 validation errors for ProcessingInput
source
Extra inputs are not permitted [type=extra_forbidden, input_value='s3://sagemaker-.../input/py-files', input_type=str]
For further information visit https://errors.pydantic.dev/2.13/v/extra_forbidden
destination
Extra inputs are not permitted [type=extra_forbidden, input_value='/opt/ml/processing/input/py-files', input_type=str]
For further information visit https://errors.pydantic.dev/2.13/v/extra_forbidden
```

The cause of the error is [here](https://github.com/aws/sagemaker-python-sdk/blob/8e7485a1ed25eb17c70f2323ab6ed6c9695d7024/sagemaker-core/src/sagemaker/core/spark/processing.py#L508-L512):

```py
input_channel = ProcessingInput(
source=input_channel_s3_uri,
destination=f"{self._conf_container_base_path}{input_channel_name}",
input_name=input_channel_name,
)
```

**System information**

- AWS SageMaker Studio 4.4.3
- sagemaker-core: 2.20
- Python 3.12.14
- uname: Linux default 6.12.103-127.188.amzn2023.x86_64 SMP PREEMPT_DYNAMIC Tue Aug 25 15:42:53 UTC 2026 x86_64 x86_64 x86_64 GNU/Linux

**Additional context**

Commencez dans sagemaker/core/spark/processing.py, au niveau du code de PySparkProcessor.run() autour des lignes 508-512, et suivez la manière dont un chemin local dans submit_py_files est converti en ProcessingInput. Le travail est terminé lorsqu’un chemin de fichier local est accepté et que le job de traitement démarre correctement sans les erreurs de validation Pydantic signalées.

Rédigé par le modèle d'indexation à partir du texte de l'issue.