docs: refresh Python workflow guidance

[CodeSigils]

Summary

• move the greenfield Python floor to 3.11 while preserving existing 3.10 contracts
• update the deployment example to Ubuntu 26.04 LTS and its Python 3.14 default
• refresh Hermes installation, Ruff notebook, pip index, payload-boundary, and review-date guidance
• add validator assertions for the refreshed contracts and synchronize runtime mirrors

Validation

• portability, CI policy, skill source, and payload validators
• CI policy and payload regression tests
• payload synchronization check
• Ruff 0.12.4, ShellCheck, Bash syntax, and diff checks
• all relative Markdown links and 15 live URLs