chore: add zizmor workflow to harden GitHub Actions security

.github/workflows/zizmor.yml

@@ -0,0 +1,45 @@
+# Analyzes all GitHub Actions workflows for security issues using zizmor.
+# docs: https://docs.zizmor.sh/
+name: Workflow Security Analysis (zizmor)
+
+on:
+  pull_request:
+    paths:
+      - ".github/workflows/**"
+  push:
+    paths:
+      - ".github/workflows/**"
+  schedule:
+    # Every Saturday at 00:00 UTC
+    - cron: "0 0 * * 6"
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  zizmor:
+    name: zizmor
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - name: Checkout
+        # see https://github.com/actions/checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
+      - name: Run zizmor
+        # see https://github.com/zizmorcore/zizmor-action
+        uses: zizmorcore/zizmor-action@b1d7e1fb5de872772f31590499237e7cce841e8e # v0.5.3
+        with:
+          # advanced-security: false => emit findings as workflow-command annotations (::error file=…) rather than
+          # uploading a SARIF report to GitHub's Security tab.
+          # Uploading SARIF requires `security-events: write` and GitHub Advanced Security (GHAS),
+          # both of which are unnecessary here and would violate the least-privilege policy.
+          # The two modes are mutually exclusive: advanced-security must be false for
+          # annotations to take effect.
+          advanced-security: false
+          annotations: true

.pre-commit-config.yaml

@@ -42,3 +42,7 @@ repos:
         entry: poetry run -- tox r -e bandit
         pass_filenames: false
         language: system
+  - repo: https://github.com/zizmorcore/zizmor-pre-commit
+    rev: v1.24.1
+    hooks:
+      - id: zizmor