[management,client] 0.75.0 release with new desktop UI (#6473)

- **Wails v3 application** (`client/ui`) with a React + TypeScript + Tailwind frontend replacing the Fyne UI: main connection view, exit-node switcher, networks/peers browser with detail panels, profile management, settings (general, network, SSH, security, troubleshooting, appearance), debug-bundle creation, and a first-run welcome flow.
- **Internationalization**: go-i18n bundle with 9 locales (en, de, es, fr, hu, it, pt, ru, zh-CN) shared between the tray and the frontend.
- **New system tray** implementation with per-platform theme-aware icons, including a native XEmbed host for Linux (`xembed_tray_linux.c`) and a Linux theme watcher.
- **Session handling**: auth session watcher (`client/internal/auth/sessionwatch`), pending login flow, session-expiration dialog and tray notifications, and `netbird login` improvements.
- **Daemon API extensions** (`daemon.proto`): status stream subscription, event stream, networks/exit-node selection endpoints, and richer full status — with probe throttling on the daemon side to protect against UI-driven request storms.
- **UI preferences store** persisted per profile, autostart management via the daemon (single source of truth in HKCU on Windows).
- **Build system**: Taskfile-based builds per platform (macOS, Linux, Windows), Docker cross-compilation images, MSIX/NSIS/nfpm/AppImage packaging, and a new `frontend-ui` CI workflow.

Co-authored-by: Zoltan Papp <zoltan.pmail@gmail.com>
Co-authored-by: Eduard Gert <kontakt@eduardgert.de>
Co-authored-by: braginini <bangvalo@gmail.com>
Co-authored-by: Pascal Fischer <32096965+pascal-fischer@users.noreply.github.com>
Co-authored-by: riccardom <riccardomanfrin@gmail.com>

client/ui/update_windows.go

@@ -1,44 +0,0 @@
-//go:build windows
-
-package main
-
-import (
-	log "github.com/sirupsen/logrus"
-	"golang.org/x/sys/windows"
-
-	nbprocess "github.com/netbirdio/netbird/client/ui/process"
-)
-
-// killParentUIProcess finds and kills the parent systray UI process on Windows.
-// This is a workaround in case the MSI installer fails to properly terminate the UI process.
-// The installer should handle this via util:CloseApplication with TerminateProcess, but this
-// provides an additional safety mechanism to ensure the UI is closed before the upgrade proceeds.
-func killParentUIProcess() {
-	pid, running, err := nbprocess.IsAnotherProcessRunning()
-	if err != nil {
-		log.Warnf("failed to check for parent UI process: %v", err)
-		return
-	}
-
-	if !running {
-		log.Debug("no parent UI process found to kill")
-		return
-	}
-
-	log.Infof("killing parent UI process (PID: %d)", pid)
-
-	// Open the process with terminate rights
-	handle, err := windows.OpenProcess(windows.PROCESS_TERMINATE, false, uint32(pid))
-	if err != nil {
-		log.Warnf("failed to open parent process %d: %v", pid, err)
-		return
-	}
-	defer func() {
-		_ = windows.CloseHandle(handle)
-	}()
-
-	// Terminate the process with exit code 0
-	if err := windows.TerminateProcess(handle, 0); err != nil {
-		log.Warnf("failed to terminate parent process %d: %v", pid, err)
-	}
-}