sigilry/sigilry: SPEC.md

# Sigilry Spec Index This is the top-level specification entrypoint for the monorepo. ## Spec TOC ### Repo-Level Specs - `SPEC.md` (this file) - `specs/README.md` (spec index and statuses) - `specs/ci-cd.spec.md` ### Package Sub-Specs - `packages/dapp/SPEC.md` - `packages/dapp/discovery.spec.md` — p