[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/server/extend_authsession_test.go

@@ -0,0 +1,42 @@
+package server
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc/codes"
+	gstatus "google.golang.org/grpc/status"
+)
+
+func TestInnermostStatus(t *testing.T) {
+	t.Run("wrapped gRPC status", func(t *testing.T) {
+		inner := gstatus.Error(codes.PermissionDenied, "peer is already registered by a different User or a Setup Key")
+		// Mirror the daemon wrap chain: engine wraps with %w, mgm error is the inner status.
+		wrapped := fmt.Errorf("extend auth session on management: %w", inner)
+
+		st := innermostStatus(wrapped)
+		require.NotNil(t, st)
+		require.Equal(t, codes.PermissionDenied, st.Code())
+		require.Equal(t, "peer is already registered by a different User or a Setup Key", st.Message())
+	})
+
+	t.Run("deepest status wins over an outer one", func(t *testing.T) {
+		inner := gstatus.Error(codes.PermissionDenied, "deepest")
+		chain := fmt.Errorf("outer: %w", fmt.Errorf("mid: %w", inner))
+
+		st := innermostStatus(chain)
+		require.NotNil(t, st)
+		require.Equal(t, codes.PermissionDenied, st.Code())
+		require.Equal(t, "deepest", st.Message())
+	})
+
+	t.Run("no status in chain", func(t *testing.T) {
+		require.Nil(t, innermostStatus(errors.New("plain error")))
+	})
+
+	t.Run("nil error", func(t *testing.T) {
+		require.Nil(t, innermostStatus(nil))
+	})
+}