ci: pin GitHub Actions to commit SHAs for security (#56)

Pin all GitHub Actions dependencies to specific commit SHAs instead
of version tags to prevent supply chain attacks. This follows OpenSSF
Scorecard best practices for dependency pinning.

Pinned actions:
- actions/checkout@v5
- actions/create-github-app-token@v2
- actions/setup-python@v6
- actions/upload-artifact@v4
- amannn/action-semantic-pull-request@v6
- astral-sh/setup-uv@v7
- codecov/codecov-action@v5
- github/codeql-action/*@V3
- github/codeql-action/*@v4
- ossf/scorecard-action@v2.4.3
- pypa/gh-action-pypi-publish@release/v1

All SHAs include comments showing the original version tag for
maintainability.

Expected impact: Pinned-Dependencies score 0 → 10

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: dreamiurg

.github/workflows/ci.yml

@@ -30,17 +30,17 @@ jobs:
     name: Lint and format check
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6
         with:
           python-version: "3.14"
           cache: pip
           cache-dependency-path: pyproject.toml
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v7
+        uses: astral-sh/setup-uv@85856786d1ce8acfbcc2f13a5f3fbd6b938f9f41 # v7
         with:
           enable-cache: true
           cache-dependency-glob: "pyproject.toml"
@@ -75,17 +75,17 @@ jobs:
             python-version: "3.14"
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6
         with:
           python-version: ${{ matrix.python-version }}
           cache: pip
           cache-dependency-path: pyproject.toml
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v7
+        uses: astral-sh/setup-uv@85856786d1ce8acfbcc2f13a5f3fbd6b938f9f41 # v7
         with:
           enable-cache: true
           cache-dependency-glob: "pyproject.toml"
@@ -98,7 +98,7 @@ jobs:
 
       - name: Upload coverage to Codecov
         if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.14'
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@5a1091511ad55cbe89839c7260b706298ca349f7 # v5
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           file: ./coverage.xml
@@ -110,7 +110,7 @@ jobs:
     if: github.event_name == 'pull_request'
     steps:
       - name: Validate PR title follows conventional commit format
-        uses: amannn/action-semantic-pull-request@v6
+        uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:

.github/workflows/codeql.yml

@@ -24,16 +24,16 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@v3
+        uses: github/codeql-action/init@5d5cd550d3e189c569da8f16ea8de2d821c9bf7a # v3
         with:
           languages: python
           # Queries: security-extended includes all security checks
           queries: security-extended
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@v3
+        uses: github/codeql-action/analyze@5d5cd550d3e189c569da8f16ea8de2d821c9bf7a # v3
         with:
           category: "/language:python"

.github/workflows/release.yml

@@ -20,26 +20,26 @@ jobs:
     steps:
       - name: Generate GitHub App token
         id: app-token
-        uses: actions/create-github-app-token@v2
+        uses: actions/create-github-app-token@67018539274d69449ef7c02e8e71183d1719ab42 # v2
         with:
           app-id: ${{ secrets.RELEASE_APP_ID }}
           private-key: ${{ secrets.RELEASE_APP_PRIVATE_KEY }}
 
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
           fetch-depth: 0
           token: ${{ steps.app-token.outputs.token }}
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6
         with:
           python-version: '3.12'
           cache: pip
           cache-dependency-path: pyproject.toml
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v7
+        uses: astral-sh/setup-uv@85856786d1ce8acfbcc2f13a5f3fbd6b938f9f41 # v7
         with:
           enable-cache: true
           cache-dependency-glob: "pyproject.toml"
@@ -68,6 +68,6 @@ jobs:
 
       - name: Publish to PyPI
         if: steps.semantic-release.outputs.new_release == 'true'
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@ed0c53931b1dc9bd32cbe73a98c7f6766f8a527e # release/v1
         with:
           print-hash: true

.github/workflows/scorecard.yml

@@ -27,26 +27,26 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
           persist-credentials: false
 
       - name: Run analysis
-        uses: ossf/scorecard-action@v2.4.3
+        uses: ossf/scorecard-action@4eaacf0543bb3f2c246792bd56e8cdeffafb205a # v2.4.3
         with:
           results_file: results.sarif
           results_format: sarif
           # Publish results to OpenSSF REST API for the badge
           publish_results: true
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: SARIF file
           path: results.sarif
           retention-days: 5
 
       - name: Upload to code-scanning
-        uses: github/codeql-action/upload-sarif@v4
+        uses: github/codeql-action/upload-sarif@0499de31b99561a6d14a36a5f662c2a54f91beee # v4
         with:
           sarif_file: results.sarif