● feat: Draft pip package policy management system (not yet integrated)

Add comprehensive pip dependency conflict resolution framework as draft implementation. This is self-contained and does not affect existing
ComfyUI Manager functionality.

Key components:
- pip_util.py with PipBatch class for policy-driven package management
- Lazy-loaded policy system supporting base + user overrides
- Multi-stage policy execution (uninstall → apply_first_match → apply_all_matches → restore)
- Conditional policies based on platform, installed packages, and ComfyUI version
- Comprehensive test suite covering edge cases, workflows, and platform scenarios
- Design and implementation documentation

Policy capabilities (draft):
- Package replacement (e.g., PIL → Pillow, opencv-python → opencv-contrib-python)
- Version pinning to prevent dependency conflicts
- Dependency protection during installations
- Platform-specific handling (Linux/Windows, GPU detection)
- Pre-removal and post-restoration workflows

Testing infrastructure:
- Pytest-based test suite with isolated environments
- Dependency analysis tools for conflict detection
- Coverage for policy priority, edge cases, and environment recovery

Status: Draft implementation complete, integration with manager workflows pending.

tests/common/pip_util/pytest.ini

@@ -0,0 +1,52 @@
+[pytest]
+# pytest configuration for pip_util.py tests
+
+# Test discovery
+testpaths = .
+
+# Markers
+markers =
+    unit: Unit tests for individual functions
+    integration: Integration tests for workflows
+    e2e: End-to-end tests for complete scenarios
+
+# Output options - extend global config
+addopts =
+    # Coverage options for pip_util
+    --cov=../../../comfyui_manager/common/pip_util
+    --cov-report=html:htmlcov_pip_util
+    --cov-report=term-missing
+    --cov-report=xml:coverage_pip_util.xml
+    # Coverage fail threshold
+    --cov-fail-under=80
+
+# Coverage configuration
+[coverage:run]
+source = ../../../comfyui_manager/common
+omit =
+    */tests/*
+    */test_*.py
+    */__pycache__/*
+    */test_venv/*
+
+[coverage:report]
+precision = 2
+show_missing = True
+skip_covered = False
+
+exclude_lines =
+    # Standard pragma
+    pragma: no cover
+    # Don't complain about missing debug code
+    def __repr__
+    # Don't complain if tests don't hit defensive assertion code
+    raise AssertionError
+    raise NotImplementedError
+    # Don't complain if non-runnable code isn't run
+    if __name__ == .__main__.:
+    # Don't complain about abstract methods
+    @abstractmethod
+
+[coverage:html]
+directory = htmlcov
+