KTailctl v0.22.0

This is a major release built on top of a near-complete rewrite of the codebase.
The backend was reimplemented from scratch around a generic property-based list model, the C++/QML integration was modernized, and the build, testing and CI infrastructure were overhauled.
On the surface, the peer list, exit node page, settings page and tray menu were redesigned, multi-account switching was reimplemented and many smaller features and bugfixes were added.

Features & Enhancements

Peer list & peer details:

• Redesign the peer list and make it load noticeably faster
• Filter peers by DNS name (case-insensitive) and by online/Mullvad status
• Sort peers by DNS name and highlight the current node
• Show tags on the peer list (optional) and on the peer info page
• Show peer details in a separate column when enough space is available
• Show location and country flag, primary routes, public key, and "last seen"/"created" timestamps
• Add descriptions and copy buttons for the individual peer details
• Add links to the Tailscale admin panel

Exit nodes:

• Redesign the exit node page to match the new peer list
• Set and unset exit nodes from the UI and the tray menu
• Group Mullvad exit nodes by country with flags and use the location for descriptions/tooltips
• Manage self-hosted exit nodes
• Toggle exit node "allow LAN access" from the exit node and settings pages
• Suggest an exit node and allow switching back to the last used one
• Filter exit nodes by DNS name, country and city

Tray menu & icon:

• Reworked tray menu with dedicated submenus for self, peers, exit nodes and accounts
• Indicate exit node usage in the tray icon
• Add a tooltip showing Tailscale status, IP and current exit node
• Add node icons (smartphone or computer) and a Mullvad icon for submenus
• Toggle Tailscale on/off and switch the tray icon theme
• Show country flags for Mullvad exit nodes grouped by country

Accounts:

• Reimplement multi-account support including switching
• Edit and refresh account names

Settings & configuration:

• New settings page wired up to Tailscale preferences (SSH server, operator, exit node LAN access, ...)
• Integrate KConfig and automatically save the application configuration
• Add a login profiles page showing detailed information about each profile

Status & error handling:

• Show an inline message when Tailscale needs to be authenticated
• Show an inline message when the user is not the Tailscale operator
• Show an inline message when tailscaled is not running

Fixes

• Fix refreshing of the Tailscale status while the window is hidden
• Fix self-hosted exit node integration
• Work around a Qt 6.10 double free with a custom string filter model
• Force the Breeze/Breeze-dark icon theme and make sure Breeze icons are used (Flatpak)
• Give the Flatpak network access so user avatars can be fetched
• Fix and homogenize the exit node list entries
• Fix the tray icon not updating on theme or backend state changes
• Many smaller UI fixes (copy buttons, filter icon, page highlighting, settings toggles, ...)

Chores

This release rewrites large parts of the project. The most relevant internal changes:

C++/QML:

• Reimplement the backend around a generic PropertyListModel and regenerated Tailscale status objects
• Use modern QML registration macros and bump the C++ standard to 23
• Enable KDE compiler settings and make the codebase comply with them

Go:

• Update tailscale.com, golang.org/x/net and the rest of the Go dependency chain
• Bump Go to the latest version supported by the Flatpak SDK extension (incl. several security fixes)
• Make golang.org/x/net an indirect dependency

Build system:

• Add infrastructure for and a large number of unit tests
• Optionally fetch and vendor the required Go version via CMake
• Dynamically discover and register country flag icons and generate themed tray icon variants

CI & tooling:

• Modularize the CI using scripts and add a native build
• Integrate clang-tidy, clazy, cppcheck, include-what-you-use, CodeQL, govulncheck, Google's OSV scanner, shellcheck and actionlint
• Run pre-commit hooks via prek and add hooks for Go, Python, QML, CMake, YAML and shell
• Switch dependency updates from Renovate to Dependabot and remove the Nix flake/devshell
• Support creating beta releases

Documentation

• Add a new README with updated screenshots
• Update the Fedora dependency scripts (including debug dependencies)