feat(build): migrate from PyOxidizer to PyInstaller for better platform support

PyOxidizer 0.24.0 has limited Python 3.11 support across platforms, causing
build failures on Windows, Linux, and macOS. PyInstaller provides broader
platform compatibility and simpler configuration.

Changes:
- Remove pyoxidizer.bzl configuration
- Update python-ci.yml to pass entry_point parameter to build workflow
- Entry point: ccproxy.cli.main:main

Related workflow changes in homebrew-packages will enable PyInstaller builds.

Author: CaddyGlow

.github/workflows/python-ci.yml

@@ -50,6 +50,7 @@ jobs:
     with:
       ref: ${{ inputs.ref || '' }}
       binary_name: ccproxy
+      entry_point: 'ccproxy.cli.main:main'
       assets: '["README.md", "LICENSE"]'
       target_preset: ${{ inputs.target_preset || 'all' }}
       python_version: '3.11'