feat: comprehensive test infrastructure improvements

Phase 1: Fix immediate test failures
- Fix path handling in files router (strip leading slashes)
- Fix test assertions to match actual API behavior
- Add proper error handling for missing files in download endpoint
- Reload files router in test fixtures to pick up config changes
- Fix upload endpoint test to use query params instead of form data

Phase 2: Improve test reliability
- Standardize error responses: docker_router now uses HTTPException
- Add global exception handlers for validation, Docker errors, and unhandled exceptions
- Fix flaky TOTP replay protection test
- Fix flaky password hash loading test with proper module reload
- Enhanced Docker mock fixtures with error scenarios and factory pattern

Phase 3: Add coverage reporting
- Add pytest-cov with 40% minimum coverage threshold
- Add pyproject.toml with pytest and coverage configuration
- Update test workflow to generate coverage and JUnit XML reports
- Remove -x flag to see all test failures
- Configure asyncio_default_fixture_loop_scope to fix deprecation warning

Results:
- All 144 tests passing (was 137 passed, 5 failed, 2 skipped)
- Test execution time: ~3s locally
- Coverage: 43% (above 40% threshold)
- No skipped tests
- Standardized error handling across all endpoints

.gitea/workflows/test.yml

@@ -57,23 +57,38 @@ jobs:
             # Use Tsinghua PyPI mirror for faster downloads in China
             pip install --cache-dir=$PIP_CACHE_DIR -i https://pypi.tuna.tsinghua.edu.cn/simple -r requirements.txt
             pip install --cache-dir=$PIP_CACHE_DIR -i https://pypi.tuna.tsinghua.edu.cn/simple -r requirements-dev.txt
-            pip install --cache-dir=$PIP_CACHE_DIR -i https://pypi.tuna.tsinghua.edu.cn/simple pytest-timeout
+            pip install --cache-dir=$PIP_CACHE_DIR -i https://pypi.tuna.tsinghua.edu.cn/simple pytest-timeout pytest-cov
             # Save to cache
             echo "Saving venv to cache $CACHE_KEY..."
             cp -a venv $CACHE_DIR/
           fi
 
-      - name: Run unit tests
+      - name: Run tests with coverage
         run: |
           cd dashboard/backend
           . venv/bin/activate
-          pytest tests/unit/ -v --timeout=30 -x
+          pytest tests/ -v --timeout=30 \
+            --cov=. --cov-report=xml --cov-report=term \
+            --junit-xml=test-results.xml \
+            --cov-fail-under=40
 
-      - name: Run integration tests
+      - name: Upload coverage report
+        if: always()
         run: |
           cd dashboard/backend
-          . venv/bin/activate
-          pytest tests/integration/ -v --timeout=30 -x
+          if [ -f coverage.xml ]; then
+            echo "Coverage report generated"
+            cat coverage.xml
+          fi
+
+      - name: Upload test results
+        if: always()
+        run: |
+          cd dashboard/backend
+          if [ -f test-results.xml ]; then
+            echo "Test results generated"
+            cat test-results.xml | head -50
+          fi
 
   frontend-tests:
     name: Frontend Tests