chore: rename to @soulcraftlabs/brainy for Open Brainy on The Source

Prepares the repo for its new home at soulcraftlabs/open-brainy ahead
of the Forgejo transfer: package name, publish registry, release
script, and every install/import reference across docs, src, tests,
examples, and integrations now point at @soulcraftlabs/brainy on
The Source. The npmjs storefront leg and byte-identity pair
verification are stripped from the release script — The Source is
now the only publish target. README gains an Open Brainy explainer
and a registry note for consumers.

@soulcraft/brainy 10.4.2 was the last release under the old name.

docs/MIGRATION-V3-TO-V4.md

@@ -153,13 +153,13 @@ brainy-data/
 ### Step 1: Update Brainy Package
 
 ```bash
-npm install @soulcraft/brainy@latest
+npm install @soulcraftlabs/brainy@latest
 ```
 
 **Check your version:**
 ```bash
-npm list @soulcraft/brainy
-# Should show: @soulcraft/brainy@4.0.0
+npm list @soulcraftlabs/brainy
+# Should show: @soulcraftlabs/brainy@4.0.0
 ```
 
 ### Step 2: No Code Changes Required! ✅
@@ -374,7 +374,7 @@ If you encounter issues, you can rollback:
 
 ```bash
 # Reinstall v3
-npm install @soulcraft/brainy@^3.50.0
+npm install @soulcraftlabs/brainy@^3.50.0
 
 # Restart application
 ```
@@ -389,7 +389,7 @@ rm -rf ./data
 cp -r ./data-backup ./data
 
 # Reinstall v3
-npm install @soulcraft/brainy@^3.50.0
+npm install @soulcraftlabs/brainy@^3.50.0
 ```
 
 ## Common Migration Scenarios
@@ -539,7 +539,7 @@ console.log('Storage type:', status.type)
 
 **Migration Checklist:**
 - ✅ Backup data
-- ✅ Update npm package (`npm install @soulcraft/brainy@latest`)
+- ✅ Update npm package (`npm install @soulcraftlabs/brainy@latest`)
 - ✅ Restart application (automatic migration)
 - ✅ Verify data integrity
 - ✅ Enable lifecycle policies