Add ShellCheck and Ruff code sniffers to CI and release workflows

- Introduce dedicated ShellCheck workflow for Bash scripts
- Add Ruff as Python code sniffer for src/ and tests/
- Integrate both sniffers into main CI pipeline
- Require successful sniffer runs before marking a release as stable
- Ensure consistent code quality checks across CI and release workflows

https://chatgpt.com/share/693d5b26-293c-800f-999d-48b2950b9417

.github/workflows/codesniffer-ruff.yml

@@ -0,0 +1,24 @@
+name: Ruff (Python code sniffer)
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  codesniffer-ruff:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install ruff
+        run: pip install ruff
+
+      - name: Run ruff
+        run: |
+          ruff check src tests