add test infrastructure and --quiet mode

- stdlib unittest suite: 38 tests for client, commands, output
- fixtures/ with load_fixture() helper and sample data
- -q/--quiet flag: tab-separated output, no headers
- ci: package syntax check, lint, test job

.gitea/workflows/ci.yml

@@ -27,8 +27,22 @@ jobs:
       - name: Install tools
         run: pip install -q ruff
 
-      - name: Syntax check
+      - name: Syntax check (entrypoint)
         run: python -m py_compile harbor-ctl.py
 
-      - name: Lint
+      - name: Syntax check (package)
+        run: |
+          for f in src/harbor/*.py; do
+            python -m py_compile "$f"
+          done
+
+      - name: Lint (entrypoint)
         run: ruff check harbor-ctl.py
+
+      - name: Lint (package)
+        run: ruff check src/harbor/
+
+      - name: Run tests
+        run: python -m unittest discover -s src/harbor/tests -v
+        env:
+          PYTHONPATH: src