v0.4.0

What's Changed

• feat(packaging): move the official one-package install into packaging/ by @Urdemonlord in #24
• fix(packaging): restore executable bits on packaging scripts by @Urdemonlord in #25
• feat(admin): create integration keys from the dashboard, store relay rejection reasons by @Urdemonlord in #26
• feat(web): integration docs as an in-app page, generated from docs/INTEGRATIONS.md by @Urdemonlord in #27
• feat(admin): DB-backed integration app registration via the admin dashboard by @Urdemonlord in #28
• feat(packaging): macOS tarballs (arm64 + amd64) with launchd services by @Urdemonlord in #29
• fix(packaging): restore executable bits on macOS scripts by @Urdemonlord in #30
• feat(packaging): upload macOS tarballs to the release on tag push by @Urdemonlord in #31
• feat(packaging): draft Homebrew formula for the macOS install by @Urdemonlord in #32
• feat(relay): multi-provider send failover (Resend, then Brevo) by @Urdemonlord in #33
• feat(compose): undo send with 10s server-side hold by @Urdemonlord in #34
• feat(compose): HTML compose with sanitizer and per-mailbox signatures by @Urdemonlord in #35
• feat(mailboxes): link multiple mail accounts to one login by @Urdemonlord in #36
• feat(admin): audit trail for logins, sends and admin actions by @Urdemonlord in #37
• feat(security): strict Content-Security-Policy for the app shell by @Urdemonlord in #38
• chore(release): bump version to 0.4.0 by @Urdemonlord in #39

Full Changelog: v0.3.0...v0.4.0