fix(ci): enforce lint failures and add pytest job to validate-config

Refs #485 - Expand Gitea CI/CD pipeline maturity

Changes:
- Remove '|| true' from shellcheck step so shell lint errors block merges
- Remove '|| true' from flake8 step so Python lint errors block merges
- Expand flake8 scope to include scripts/, bin/, tests/
- Exclude .git/ from shellcheck file discovery
- Add python-test job that runs pytest on the test suite after syntax check passes

.gitea/workflows/validate-config.yaml

@@ -59,7 +59,21 @@ jobs:
       - name: Flake8 critical errors only
         run: |
           flake8 --select=E9,F63,F7,F82 --show-source --statistics \
-            scripts/ allegro/ cron/ || true
+            scripts/ bin/ tests/
+
+  python-test:
+    name: Python Test Suite
+    runs-on: ubuntu-latest
+    needs: python-check
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+      - name: Install test dependencies
+        run: pip install pytest pyyaml
+      - name: Run tests
+        run: python3 -m pytest tests/ -v --tb=short
 
   shell-lint:
     name: Shell Script Lint
@@ -70,7 +84,7 @@ jobs:
         run: sudo apt-get install -y shellcheck
       - name: Lint shell scripts
         run: |
-          find . -name '*.sh' -print0 | xargs -0 -r shellcheck --severity=error || true
+          find . -name '*.sh' -not -path './.git/*' -print0 | xargs -0 -r shellcheck --severity=error
 
   cron-validate:
     name: Cron Syntax Check