feat: Implement longest_positive_streak function

Adds the `longest_positive_streak` function and accompanying tests.
Includes a GitHub Actions workflow to run tests on push and pull request.
Adds a .gitignore file to exclude python cache files.

Author: google-labs-jules[bot]

.github/workflows/pytest.yml

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+name: Pytest
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.x'
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install pytest
+    - name: Test with pytest
+      run: |
+        pytest

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# PyInstaller
+#  Usually these files are created by a PyInstaller bundle and not checked into
+#  git, but they may be mistakenly added when commands are run outside of a
+#  virtualenv.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyderworkspace
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/

streak.py

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+def longest_positive_streak(nums: list[int]) -> int:
+    """
+    Returns the length of the longest run of consecutive values strictly greater than 0.
+
+    An empty list returns 0.
+
+    Non-positive numbers (0 or negative) break the streak.
+
+    Must be deterministic and pure: no randomness, prints, or global state.
+    """
+    max_streak = 0
+    current_streak = 0
+    for num in nums:
+        if num > 0:
+            current_streak += 1
+        else:
+            max_streak = max(max_streak, current_streak)
+            current_streak = 0
+    max_streak = max(max_streak, current_streak)
+    return max_streak

tests/test_streak.py

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+import pytest
+from streak import longest_positive_streak
+
+def test_empty_list():
+    assert longest_positive_streak([]) == 0
+
+def test_no_positive_numbers():
+    assert longest_positive_streak([-1, -2, 0]) == 0
+
+def test_single_streak():
+    assert longest_positive_streak([1, 2, 3]) == 3
+
+def test_multiple_streaks():
+    assert longest_positive_streak([1, 2, 0, 1, 2, 3, 0, 1]) == 3
+
+def test_streaks_with_negatives():
+    assert longest_positive_streak([1, 2, -1, 1, 2, 3, -2, 1]) == 3
+
+def test_zeros_breaking_streaks():
+    assert longest_positive_streak([1, 0, 2, 3, 0, 4, 5, 6]) == 3
+
+def test_leading_zeros():
+    assert longest_positive_streak([0, 0, 1, 2, 3]) == 3
+
+def test_trailing_zeros():
+    assert longest_positive_streak([1, 2, 3, 0, 0]) == 3