[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/updater/state.go

@@ -0,0 +1,97 @@
+//go:build !android && !ios && !freebsd && !js
+
+// Package updater holds the auto-update domain: the typed State, the
+// daemon-SystemEvent metadata schema, and the Holder that caches the latest
+// state and broadcasts changes. No Wails dependency.
+package updater
+
+import (
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/proto"
+)
+
+// EventStateChanged carries the full State snapshot as payload.
+const EventStateChanged = "netbird:update:state"
+
+// State is the typed snapshot of the daemon's update situation. Installing is
+// driven only by the daemon's progress_window:show event; a UI-side
+// Update.Trigger() does not flip it.
+type State struct {
+	Available  bool   `json:"available"`
+	Version    string `json:"version"`
+	Enforced   bool   `json:"enforced"`
+	Installing bool   `json:"installing"`
+}
+
+// Emitter is the broadcast dependency Holder needs; the Wails app.Event
+// processor satisfies it.
+type Emitter interface {
+	Emit(name string, data ...any) bool
+}
+
+// Holder caches the latest update State and broadcasts changes.
+type Holder struct {
+	emitter Emitter
+
+	mu    sync.Mutex
+	state State
+}
+
+// NewHolder constructs an empty-state Holder. A nil emitter skips the broadcast.
+func NewHolder(emitter Emitter) *Holder {
+	return &Holder{emitter: emitter}
+}
+
+// Get returns a copy of the cached State.
+func (h *Holder) Get() State {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return h.state
+}
+
+// OnSystemEvent folds update-related metadata into the cached state, emitting
+// EventStateChanged only on an actual change so repeated daemon snapshots
+// don't produce redundant pushes.
+func (h *Holder) OnSystemEvent(ev *proto.SystemEvent) {
+	md := ev.GetMetadata()
+	if len(md) == 0 {
+		return
+	}
+
+	h.mu.Lock()
+	changed := false
+	if v, ok := md["new_version_available"]; ok {
+		_, enforced := md["enforced"]
+		if !h.state.Available || h.state.Version != v || h.state.Enforced != enforced {
+			h.state.Available = true
+			h.state.Version = v
+			h.state.Enforced = enforced
+			changed = true
+		}
+	}
+	if md["progress_window"] == "show" {
+		if !h.state.Installing {
+			h.state.Installing = true
+			changed = true
+		}
+		if v, ok := md["version"]; ok && v != "" && h.state.Version != v {
+			h.state.Version = v
+			h.state.Available = true
+			changed = true
+		}
+	}
+	snap := h.state
+	h.mu.Unlock()
+
+	if !changed {
+		return
+	}
+	log.Infof("update state: available=%v version=%q enforced=%v installing=%v",
+		snap.Available, snap.Version, snap.Enforced, snap.Installing)
+	if h.emitter != nil {
+		h.emitter.Emit(EventStateChanged, snap)
+	}
+}