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.

package.json

@@ -128,13 +128,13 @@
   "publishConfig": {
     "access": "public"
   },
-  "homepage": "https://github.com/soulcraftlabs/brainy",
+  "homepage": "https://source.soulcraft.com/soulcraft/brainy",
   "bugs": {
-    "url": "https://github.com/soulcraftlabs/brainy/issues"
+    "url": "https://source.soulcraft.com/soulcraft/brainy/issues"
   },
   "repository": {
     "type": "git",
-    "url": "git+https://github.com/soulcraftlabs/brainy.git"
+    "url": "git+https://source.soulcraft.com/soulcraft/brainy.git"
   },
   "files": [
     "dist/**/*.js",