Release 4.0.0

What's Changed

• Implement site-level PLG analytics for Mixpanel by @noeltock in humanmade/accelerate#496
• Add E2E test for A/B title test creation flow by @joehoyle in humanmade/accelerate#501
• Fix: Remove variant block margin gap in editor (#456) by @noeltock in humanmade/accelerate#509
• Fix SVN tag copy failure for PR builds with slashes in branch names by @Copilot in humanmade/accelerate#514
• Fix: Layout inheritance and empty paragraphs on synced pattern promotion by @noeltock in humanmade/accelerate#511
• Remove Cognito references, migrate localStorage keys by @noeltock in humanmade/accelerate#502
• Replace Altis with Accelerate Logos in wp-admin by @noeltock in humanmade/accelerate#516
• Fix audience picker overflow on Analytics page by @noeltock in humanmade/accelerate#515
• Replace external screenshot API with native BlockPreview by @noeltock in humanmade/accelerate#503
• Fix: Broadcast modal UX improvements and save reliability by @noeltock in humanmade/accelerate#507
• Abilities API by @noeltock in humanmade/accelerate#506
• Fix flaky tests by @joehoyle in humanmade/accelerate#517
• UI Upgrade: Tailwind v4 + shadcn/ui components by @noeltock in humanmade/accelerate#523
• Show response headers on OAuth JSON parse errors by @joehoyle in humanmade/accelerate#524
• Fix duplicate store registration warnings by @joehoyle in humanmade/accelerate#520
• Fix: Filter trailing empty paragraphs instead of hiding all empty blocks by @noeltock in humanmade/accelerate#521
• Feature - Page/Post Accelerate Bar by @noeltock in humanmade/accelerate#458
• Fix release workflow authentication error by @Copilot in humanmade/accelerate#528
• Final Tweaks 4.0.0 by @noeltock in humanmade/accelerate#532
• Improve BlockPreview resolution and background color handling by @noeltock in humanmade/accelerate#534
• Add realtime graph by @rmccue in humanmade/accelerate#342
• Bayesian A/B Testing Implementation by @noeltock in humanmade/accelerate#454
• Fix stats and posts cache shared across different periods by @joehoyle in humanmade/accelerate#541
• Fix audience estimate display issues by @joehoyle in humanmade/accelerate#536
• Fix duplicate values in audience rule select dropdown by @joehoyle in humanmade/accelerate#537
• Fix z-index for portal UI components to appear above WP admin menu by @joehoyle in humanmade/accelerate#535
• Fix variants dropdown height limit cutting off content by @noeltock in humanmade/accelerate#546
• Feat: Add HMAC-authenticated remote API endpoints by @joehoyle in humanmade/accelerate#547

Full Changelog: humanmade/accelerate@3.5.4...4.0.0