docs/DISTRIBUTION_SETUP.md one-time secrets runbook

[ulises-jeremias]

Summary

Operator runbook for all distribution secrets.

CNA mapping

CNA: docs/DISTRIBUTION_SETUP.md.

Acceptance criteria

• Lists every secret and where to create it
• PyPI trusted publisher steps
• Docker/AUR/Brew sections

Blocked by

none

Blocks

none

Reference

Parity matrix (workspace): knowledge/create-python-app-parity-matrix.md
Reference repo: https://github.com/Create-Node-App/create-node-app

Parent epic

#9