chore: Improve py-shiny release skill with lessons from v1.6.1

[cpsievert]

Summary

• Add GH Release naming conventions table (required title prefixes for PyPI publish workflows)
• Document parallelism opportunities for independent later phases (8-12)
• Clarify py-htmltools version bump format and changelog conventions
• Expand shinylive phase: all Python submodules must be updated (not just py-shiny), lockfile verification, deploy workflow details
• Add specific file paths for py-shinylive version bumps
• Expand r-shinylive phase: DESCRIPTION version bump and NEWS.md entry
• Clarify py-shiny docs bump targets [doc] extras in pyproject.toml
• Document conda-forge known issues (stale license_file references, bot PR timing)
• Update Huggingface phase: Space uses unpinned deps, restart-first troubleshooting
• Codify tag-before-push-main ordering for safer releases

Test plan

• These are Claude Code skill files (markdown only) — no code changes to test