chore: the forge is the address — retire the archived mirror from every live surface

Ruled today: the project's one public home is source.soulcraft.com. The
old public repo is archived history and no longer part of any release.

- package.json repository/homepage/bugs now point at the forge (this is
  what the npm page links as Repository/Homepage/Issues)
- README CI badge reads the forge pipeline; CONTRIBUTING drops the
  mirror paragraph (forge account or email patch were already the ruled
  contribution paths)
- release.sh: mirror push + external release step removed; publishes go
  forge-first (box-held write token, temp userconfig so the token never
  hits argv; a forge-publish failure aborts before the storefront so the
  pair can never diverge), then npmjs with the scope-override pin (the
  fleet npmrc maps @soulcraft to the forge and scope mappings beat
  --registry); release page created via forge API when a token is
  present, loud skip otherwise; changelog compare links point home
- dead external CI workflow removed (.forgejo/workflows/ci.yml is the
  live pipeline)

Historical CHANGELOG links to the archive stay as written - history is
history and the archive serves them read-only.

README.md

@@ -13,7 +13,7 @@
 <p align="center">
   <a href="https://www.npmjs.com/package/@soulcraft/brainy"><img src="https://img.shields.io/npm/v/@soulcraft/brainy.svg" alt="npm version"></a>
   <a href="https://www.npmjs.com/package/@soulcraft/brainy"><img src="https://img.shields.io/npm/dm/@soulcraft/brainy.svg" alt="npm downloads"></a>
-  <a href="https://github.com/soulcraftlabs/brainy/actions/workflows/ci.yml"><img src="https://github.com/soulcraftlabs/brainy/actions/workflows/ci.yml/badge.svg" alt="CI"></a>
+  <a href="https://source.soulcraft.com/soulcraft/brainy/actions"><img src="https://source.soulcraft.com/soulcraft/brainy/actions/workflows/ci.yml/badge.svg?branch=main" alt="CI"></a>
   <a href="https://soulcraft.com/docs"><img src="https://img.shields.io/badge/docs-soulcraft.com-blue.svg" alt="Documentation"></a>
   <a href="LICENSE"><img src="https://img.shields.io/badge/license-MIT-blue.svg" alt="MIT License"></a>
   <a href="https://www.typescriptlang.org/"><img src="https://img.shields.io/badge/%3C%2F%3E-TypeScript-%230074c1.svg" alt="TypeScript"></a>