Replace pkg_resources with packaging for Python 3.13/3.14 support

[mike1872ai]

Summary

Migrates all pkg_resources usage to the packaging library, enabling Python 3.13 and 3.14 support. Bumps version to 1.1.0.

Key changes

• Replaced pkg_resources with packaging across 17 source files and 13 test files (~90 call sites)
  • pkg_resources.Requirement.parse() → packaging.requirements.Requirement()
  • pkg_resources.parse_version() → packaging.version.Version()
  • .project_name → .name, .specs → .specifier, version in req → req.specifier.contains()
• New EggInfoDistInfo class in containers.py replaces PkgResourcesDistInfo — manually parses PKG-INFO and requires.txt from .egg-info directories
• Fixed Windows path handling in source.py and extractor.py — normalized paths before comparison to handle mixed separators on Windows 3.13+
• Deprecated module fixes: distutils.util.get_platform() → sysconfig.get_platform(), distutils.core wrapped in try/except, imp → importlib fallback
• CI: Python 3.13 and 3.14 added to test matrix (3 platforms × 6 versions = 18 jobs)
• Dev tools: Upgraded pylint 3.1→3.3.5, mypy 1.4→1.15, astroid 3.1→3.3.8 for 3.13/3.14 support
• Minimum Python bumped to 3.9, removed typed-ast and typing_extensions as direct deps
• Version: 1.0.0 → 1.1.0

Scope

• 47 files changed, 792 insertions, 850 deletions
• Zero pkg_resources imports remain in source code

Test plan

• pytest: 363 passed, 1 skipped (local, Python 3.10)
• mypy: no issues in 26 source files
• pylint: 10.00/10
• black/isort: all files properly formatted
• CI matrix: 3.9–3.14 × Linux/macOS/Windows
• Bazel tests

Closes #126