Captures the approved architectural pivot from horizontal Clean Architecture packages to vertical feature packages with core-* foundation packages, per the source spec (v1 + addenda v3/v4/v5) and 12 brainstorming decisions (big-bang migration, per-feature InversifyJS containers, integrations/ folder rename, controllers retained, etc.). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>