[client] Add Wails3 + React desktop UI scaffold

Stage 1 of the client/ui (Fyne) replacement. Adds a new client/ui-wails
module that runs on Linux/macOS/Windows from a single React + Vite +
Tailwind frontend driven by a thin gRPC services layer in Go.

- Single-module integration (no submodule): merge Wails3 into root go.mod
  with build tags !android !ios !freebsd !js so cross-compiles on those
  targets exclude the package automatically.
- Seven gRPC-bound services: Connection, Settings, Networks, Profiles,
  Debug, Update, Peers. Peers bridges Status polling and SubscribeEvents
  to the Wails event bus (netbird:status, netbird:event).
- Tray + window shell mirrors the Fyne menu 1:1 with hide-on-close,
  SIGUSR1 / Windows named-event for external "show window" triggers.
- React pages cover functional parity for Status, Settings (3 tabs),
  Networks (3 tabs), Profiles, Debug, Update, QuickActions, LoginUrl.
- SVG-sourced tray icons (12 source SVGs incl. macOS template variants)
  rasterized to PNG via task common:generate:tray:icons.
- Linux launcher sets WEBKIT_DISABLE_DMABUF_RENDERER=1 in the .desktop
  Exec= line and in task linux:run so the app renders correctly under
  RDP, VirtualBox, KVM, and bare WMs (Fluxbox/dwm) without DRM access.

client/ui-wails/grpc.go

@@ -0,0 +1,57 @@
+//go:build !android && !ios && !freebsd && !js
+
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+	"sync"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+
+	"github.com/netbirdio/netbird/client/proto"
+	"github.com/netbirdio/netbird/client/ui/desktop"
+)
+
+// Conn is a lazy, lock-protected gRPC connection to the NetBird daemon.
+// One Conn instance is shared by all services so they reuse the same channel.
+type Conn struct {
+	addr string
+
+	mu     sync.Mutex
+	client proto.DaemonServiceClient
+}
+
+func NewConn(addr string) *Conn {
+	return &Conn{addr: addr}
+}
+
+func (c *Conn) Client() (proto.DaemonServiceClient, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.client != nil {
+		return c.client, nil
+	}
+
+	cc, err := grpc.NewClient(
+		strings.TrimPrefix(c.addr, "tcp://"),
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithUserAgent(desktop.GetUIUserAgent()),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("dial daemon: %w", err)
+	}
+	c.client = proto.NewDaemonServiceClient(cc)
+	return c.client, nil
+}
+
+// DaemonAddr returns the default daemon gRPC address for the current OS.
+// Linux/macOS use a Unix socket; Windows uses TCP loopback.
+func DaemonAddr() string {
+	if runtime.GOOS == "windows" {
+		return "tcp://127.0.0.1:41731"
+	}
+	return "unix:///var/run/netbird.sock"
+}