[CI] Add automated monthly PyPI release plan with hotfix support

[Copilot]

Automated release system for Mooncake wheel packages with monthly cadence and hotfix support.

Description

• Monthly automated releases (1st of each month, minor version bump)
• Hotfix support via PEP 440 post versions (e.g., 0.4.0.post1)
• Release manager CLI for version management
• Multi-variant builds: CUDA/Non-CUDA, Python 3.10–3.13
• GitHub Release creation with auto-generated notes and PyPI publishing
• Backward compatible with existing tag-based releases

Removed auto-generated RELEASE_IMPLEMENTATION_SUMMARY.md as it was an unnecessary Claude artifact.

Type of Change

• Types
  • Bug fix
  • New feature
    • Transfer Engine
    • Mooncake Store
    • Mooncake EP
    • Integration
    • P2P Store
    • Python Wheel
  • Breaking change
  • CI/CD
  • Documentation update
  • Other

How Has This Been Tested?

Workflow syntax validated; release automation tested via dry-run review of version bump logic and tag generation.

Checklist

• I have performed a self-review of my own code.
• I have formatted my own code using ./scripts/code_format.sh before submitting.
• I have updated the documentation.
• I have added tests to prove my changes are effective.

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