refactor(web): clean up systray platform build files

Separate embedded tray icons into platform-specific files, rename the
no-cgo systray stub for consistency, and add the app version to the
launcher startup log.

web/backend/main.go

@@ -98,7 +98,7 @@ func main() {
 		defer logger.DisableFileLogging()
 	}
 
-	logger.InfoC("web", "PicoClaw Launcher starting...")
+	logger.InfoC("web", fmt.Sprintf("%s Launcher %s starting...", appName, appVersion))
 	logger.InfoC("web", fmt.Sprintf("PicoClaw Home: %s", picoHome))
 
 	// Set language from command line or auto-detect

web/backend/systray.go

@@ -3,7 +3,6 @@
 package main
 
 import (
-	_ "embed"
 	"fmt"
 
 	"fyne.io/systray"
@@ -93,8 +92,3 @@ func onReady() {
 func onExit() {
 	logger.Info(T(Exiting))
 }
-
-// getIcon returns the system tray icon
-func getIcon() []byte {
-	return iconData
-}

web/backend/systray_icon_nonwindows.go

@@ -0,0 +1,12 @@
+//go:build !windows && ((!darwin && !freebsd) || cgo)
+
+package main
+
+import _ "embed"
+
+//go:embed icon.png
+var iconPNG []byte
+
+func getIcon() []byte {
+	return iconPNG
+}

web/backend/systray_icon_windows.go

@@ -5,4 +5,8 @@ package main
 import _ "embed"
 
 //go:embed icon.ico
-var iconData []byte
+var iconICO []byte
+
+func getIcon() []byte {
+	return iconICO
+}

web/backend/systray_stub_nocgo.go

@@ -13,6 +13,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/logger"
 )
 
+// runTray falls back to a headless mode on platforms where systray requires cgo.
 func runTray() {
 	logger.Infof("System tray is unavailable in %s builds without cgo; running without tray", runtime.GOOS)
 

web/backend/systray_unix.go

@@ -1,8 +0,0 @@
-//go:build !windows
-
-package main
-
-import _ "embed"
-
-//go:embed icon.png
-var iconData []byte