feat(config, validation): enhance config validation with strict mode and update example checks

- Added a `--strict` option to `validate_config.py` to fail on "Unknown section" messages, aimed at CI validation of example configs.
- Updated GitHub Actions workflow to validate shipped example configs against the canonical section list using the new strict mode.
- Expanded the `CANONICAL_NON_COMMAND_SECTIONS` in `config_validation.py` to include additional sections for improved validation accuracy.
- Introduced a regression test to ensure example configs do not trigger unknown section warnings, maintaining consistency with the canonical list.

.github/workflows/test.yml

@@ -75,6 +75,16 @@ jobs:
       - name: Log injection check — fail on new unsanitized logger calls
         run: python scripts/check_log_injection.py
 
+      - name: Config validation — fail on unrecognized sections in shipped configs
+        run: |
+          set -e
+          for f in config.ini.example config.ini.minimal-example config.ini.quickstart config.min.ini config-pymc.ini; do
+            if [ -f "$f" ]; then
+              echo "Validating $f"
+              python validate_config.py --config "$f" --strict
+            fi
+          done
+
   typecheck:
     name: Type check (mypy)
     runs-on: ubuntu-latest