[client] UI refactor (#6069)

Refactor UI

---------

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: Claude <noreply@anthropic.com>
Co-authored-by: riccardom <riccardomanfrin@gmail.com>

client/ui/services/compat.go

@@ -0,0 +1,40 @@
+//go:build !android && !ios && !freebsd && !js
+
+package services
+
+import (
+	"context"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	"github.com/netbirdio/netbird/client/proto"
+)
+
+// Compat answers whether the running daemon is new enough to drive this UI.
+type Compat struct {
+	conn DaemonConn
+}
+
+func NewCompat(conn DaemonConn) *Compat {
+	return &Compat{conn: conn}
+}
+
+// DaemonReady probes the WailsUIReady RPC once. A true result means the daemon
+// implements it and is compatible. An Unimplemented response means the daemon
+// predates this UI and is too old; the caller should surface an upgrade prompt.
+// Any other error (daemon not running, transport failure) is returned so the
+// frontend can tell "outdated" apart from "not reachable".
+func (c *Compat) DaemonReady(ctx context.Context) (bool, error) {
+	client, err := c.conn.Client()
+	if err != nil {
+		return false, err
+	}
+	if _, err := client.WailsUIReady(ctx, &proto.WailsUIReadyRequest{}); err != nil {
+		if st, ok := status.FromError(err); ok && st.Code() == codes.Unimplemented {
+			return false, nil
+		}
+		return false, err
+	}
+	return true, nil
+}