Advance development after v0.2.6 - #26

Summary

• advance source development to 0.2.7.dev0
• mark the v0.2.6 quality record released and regenerate development PyPI links
• record the exact tag, workflow, public artifact hashes, and independent install verification

Release evidence

• tag commit: 59fe738
• release workflow: https://github.com/DaoyuanLi2816/mini-verl/actions/runs/30722451004
• wheel SHA-256: 11d6b001752c41a0100f12c29b125a9dc082703dbeadc6b0317a88ac818d8695
• sdist SHA-256: 91e7b2918286c342cacaf2582dbed57c1e7a1bf4e1064d327e349b1d77c28886
• independent no-cache Python 3.10 public install passed --version and doctor without training dependencies

Validation

• Ruff check and format check
• mypy: 77 source files
• packaging and Markdown/PyPI generator: 85 tests
• full non-GPU/non-network suite: 1348 passed, 6 deselected
• frozen benchmark SHA-256 unchanged: 53fc1d4d5b7adee09618d77ad62d4086ba56b78569832d6fc7c3bcd5c2695bbc