Use uv run python3 x.py instead of uv run x.py (#13966)

### Use uv run python3 x.py instead of uv run x.py

When directly call `uv run x.py` it will use the python in shebang, it
does not work if the default python lack of some packages, so change it
to best practices `uv run python3 x.py`

### Type of change

- [x] Documentation Update

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

## Release Notes

* **Documentation**
* Updated development setup instructions across all README files
(English and multiple language translations) to use explicit Python
interpreter invocation for the dependency download command.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

README_pt_br.md

@@ -320,7 +320,7 @@ docker build --platform linux/amd64 \
    git clone https://github.com/infiniflow/ragflow.git
    cd ragflow/
    uv sync --python 3.12 # instala os módulos Python dependentes do RAGFlow
-   uv run download_deps.py
+   uv run python3 download_deps.py
    pre-commit install
    ```
 3. Inicie os serviços dependentes (MinIO, Elasticsearch, Redis e MySQL) usando Docker Compose: