chore: release 1.0.0-beta.3 - #29

Summary

• bump the monorepo and public causescope package to 1.0.0-beta.3
• promote the completed Node/Windows/SWC, React stability, performance-budget, StackBlitz, roadmap, and community work from Unreleased into the beta.3 changelog

Validation

• pnpm check
• packed causescope-1.0.0-beta.3.tgz installed and transformed under Vite 5.4, 6.4, 7.3, and 8.1
• production marker scan and performance budgets passed
• standalone StackBlitz lab intentionally remains on beta.2 until the npm publish succeeds; the verifier permits exactly one beta of release lag

Release

After merge, push v1.0.0-beta.3 to trigger the trusted-publishing workflow and GitHub prerelease. Then update the standalone StackBlitz lockfile to beta.3 in a follow-up PR.