Add mypy presubmit workflow for Python samples

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

This helps detect type errors early and improves the overall user experience,
as requested in issue #13303.

The workflow runs on pull requests that modify Python sample files, installs
mypy and the sample dependencies, and performs type checking with:
    mypy samples/python --ignore-missing-imports

This presubmit aligns the samples with recommended typing practices and makes
type failures visible before merge.

Closes #13303.

Author: Shriya-23

.github/workflows/mypy-presubmit.yml

@@ -0,0 +1,30 @@
+name: mypy-presubmit
+
+on:
+  pull_request:
+    paths:
+      - "samples/python/**"
+      - ".github/workflows/mypy-presubmit.yml"
+
+jobs:
+  type-check:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.11"
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install mypy
+          pip install -r samples/python/requirements.txt || true
+
+      - name: Run mypy on samples
+        run: |
+          mypy samples/python --ignore-missing-imports