sigilry/sigilry: examples/demo-app/SPEC.md

# Demo App Spec ## Overview `examples/demo-app` is the integration reference app for local development. ## Scope - Exercise `@sigilry/dapp`, `@sigilry/react`, and `@sigilry/cli` together. - Provide a reproducible local flow for: - provider discovery (the demo wallet announces over `canton:announcePr