Set window icon on Admin Panel (title bar + taskbar)

Embed the blue SyncWarden shield icon in the panel binary and set it
as the window icon via Win32 SendMessage/WM_SETICON on startup.
Uses the syncing (blue) variant as the status-independent panel icon.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/panel/icon_other.go

@@ -0,0 +1,7 @@
+//go:build !windows
+
+package main
+
+import "unsafe"
+
+func setWindowIcon(windowPtr unsafe.Pointer) {}

cmd/panel/icon_windows.go

@@ -0,0 +1,85 @@
+//go:build windows
+
+package main
+
+import (
+	"bytes"
+	_ "embed"
+	"encoding/binary"
+	"os"
+	"path/filepath"
+	"syscall"
+	"unsafe"
+)
+
+//go:embed panel_icon.png
+var panelIconPNG []byte
+
+func setWindowIcon(windowPtr unsafe.Pointer) {
+	hwnd := uintptr(windowPtr)
+	if hwnd == 0 {
+		return
+	}
+
+	// Write a temp ICO file (Windows LoadImage needs a file path)
+	icoData := wrapPNG(panelIconPNG, 64, 64)
+	icoPath := filepath.Join(os.TempDir(), "syncwarden-panel.ico")
+	if err := os.WriteFile(icoPath, icoData, 0644); err != nil {
+		return
+	}
+
+	user32 := syscall.NewLazyDLL("user32.dll")
+	loadImage := user32.NewProc("LoadImageW")
+	sendMessage := user32.NewProc("SendMessageW")
+
+	pathW, _ := syscall.UTF16PtrFromString(icoPath)
+
+	const (
+		imageIcon      = 1
+		lrLoadFromFile = 0x0010
+		wmSetIcon      = 0x0080
+		iconBig        = 1
+		iconSmall      = 0
+	)
+
+	hBig, _, _ := loadImage.Call(0, uintptr(unsafe.Pointer(pathW)), imageIcon, 32, 32, lrLoadFromFile)
+	if hBig != 0 {
+		sendMessage.Call(hwnd, wmSetIcon, iconBig, hBig)
+	}
+
+	hSmall, _, _ := loadImage.Call(0, uintptr(unsafe.Pointer(pathW)), imageIcon, 16, 16, lrLoadFromFile)
+	if hSmall != 0 {
+		sendMessage.Call(hwnd, wmSetIcon, iconSmall, hSmall)
+	}
+}
+
+func wrapPNG(pngData []byte, width, height int) []byte {
+	const headerSize = 6
+	const entrySize = 16
+	imageOffset := headerSize + entrySize
+
+	buf := new(bytes.Buffer)
+	binary.Write(buf, binary.LittleEndian, uint16(0))
+	binary.Write(buf, binary.LittleEndian, uint16(1))
+	binary.Write(buf, binary.LittleEndian, uint16(1))
+
+	w := byte(width)
+	if width >= 256 {
+		w = 0
+	}
+	h := byte(height)
+	if height >= 256 {
+		h = 0
+	}
+	buf.WriteByte(w)
+	buf.WriteByte(h)
+	buf.WriteByte(0)
+	buf.WriteByte(0)
+	binary.Write(buf, binary.LittleEndian, uint16(1))
+	binary.Write(buf, binary.LittleEndian, uint16(32))
+	binary.Write(buf, binary.LittleEndian, uint32(len(pngData)))
+	binary.Write(buf, binary.LittleEndian, uint32(imageOffset))
+
+	buf.Write(pngData)
+	return buf.Bytes()
+}

cmd/panel/main.go

@@ -19,6 +19,10 @@ func main() {
 
 	w.SetTitle("SyncWarden — Admin Panel")
 	w.SetSize(1024, 768, webview.HintNone)
+
+	// Set window icon (title bar + taskbar)
+	setWindowIcon(w.Window())
+
 	w.Navigate(*addr)
 	w.Run()
 }