ci: add mypy presubmit workflow for Python samples

[Shriya-23]

Summary
This PR adds a GitHub Actions presubmit workflow that runs mypy on the Python samples directory.

Details

• The workflow runs automatically on pull requests that modify Python sample files.
• It installs mypy and the sample dependencies.
• It performs type checking with:
  mypy samples/python --ignore-missing-imports
• This helps catch type errors early and improves the developer experience for anyone using or contributing to the samples.

Motivation
As requested in issue #13303, adding a presubmit ensures that type failures in Python samples are detected before merging, preventing runtime errors for end users and maintaining code quality.

How to Test

• This workflow will run automatically on all new pull requests affecting the samples.

What was done in this PR
Step 1 Created a new workflow file**: workflows/mypy-presubmit.yml inside the .github/ folder.
Step 2 Configured the workflow to run on pull requests** that modify Python sample files (samples/python/**).
Step 3 Installed dependencies** in the workflow:

• mypy for type checking
• requirements.txt from the samples folder (if it exists)
  step 4 Added a mypy type check step**:

mypy samples/python --ignore-missing-imports did we 100% do this in 

References
- Closes #13303

[gemini-code-assist]

Note

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