Update to version v0.7.1.

🆕 Features

• Added .github/workflows compilation on GitHub-hosted runners for Windows amd64 and Ubuntu 22.04 AppImage.
• App connection status indicator — header icon turns green when MQTT connection is online.

🛠 Fixes

• README.md - updated
• Fixed libraries for building appimage for Ubuntu 2204. The build also works on the latest versions 2404 and 2504.
• Fixed a newer version of rustc 1.84.00.
• Refactoring of emit_event calls.
• Server configuration dialog extracted into a separate ServerConfigDialog component.
• Theme selector redesigned from dropdown to icon button toggle (Light/Auto/Dark).