release: prepare 1.0.0-beta.8 - #56

What changed

• Bump the workspace and public causescope package to 1.0.0-beta.8.
• Add the beta.8 release notes covering derived condition tracing, sensitive-value redaction, network confidence, the refund demo, and the Vite-first/Next.js support boundary.

Why

PR #55 merged package behavior and public assets without changing the published npm version. This release metadata makes that merged implementation publishable through the repository's trusted-publishing workflow.

Release path

After this PR merges, tag the resulting main commit as v1.0.0-beta.8. The existing Release workflow validates the tag, reruns pnpm check, publishes with npm provenance under the beta dist-tag, and creates a GitHub prerelease.

Validation

• pnpm check
• Package verification on Vite 5.4, 6.4, 7.3, and 8.1
• 12 React 19 Chromium E2E scenarios
• React 18 and React SWC E2E coverage
• Production runtime removal, performance budgets, public API, release metadata, links, trace contract, and StackBlitz verification