Release 0.9.0

This release packs a cleanup of the backend and build system, correct JSON handling on the go side. The API is mostly good now, this should be one of the last releases before 1.0.0.

Other changes

• Initial newsletter support by @f321x
• Migrate project to uv-managed environment by @Labfox in #400
• Fix QR code regression and backend memory leak by @Labfox in #399
• Enhance project documentation by @Labfox in #401
• Version Bumps

Full Changelog: 0.3.3...0.9.0