fix: Windows installer server launch and auto-start issues

- Remove --tray flag from LaunchServer() on Windows (notray build)
- Switch schtasks from PowerShell Register-ScheduledTask to schtasks CLI
  for Chinese Windows compatibility
- Remove /RL HIGHEST from schtasks (requires admin privileges)
- Add install log output to %TEMP%/edgeai-install.log
- Add critical flag to install steps (critical failures abort)
- Fix extractDir: create parent dirs before writing files
- Improve findPython3: skip Windows Store stub, auto-install via winget
- Enhance installLibusb: extract bundled DLL, fallback to winget

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

edge-ai-platform/installer/app.go

@@ -614,7 +614,12 @@ func (inst *Installer) LaunchServer() (string, error) {
 	binPath := filepath.Join(installDir, binName)
 
 	// Read config to get relay args
-	args := []string{"--tray"}
+	// Note: on Windows the server is built with CGO_ENABLED=0 -tags notray,
+	// so --tray is not available. On macOS the tray-enabled build is used.
+	var args []string
+	if runtime.GOOS != "windows" {
+		args = append(args, "--tray")
+	}
 	cfgPath := filepath.Join(platformConfigDir(), "config.json")
 	if data, err := os.ReadFile(cfgPath); err == nil {
 		var cfg map[string]interface{}

edge-ai-platform/installer/platform_windows.go

@@ -137,11 +137,11 @@ func installAutoRestart(installDir string) error {
 
 	// Use schtasks instead of PowerShell Register-ScheduledTask
 	// to avoid XML parsing issues on non-English Windows
+	// Note: do not use /RL HIGHEST — it requires admin privileges
 	cmd := exec.Command("schtasks", "/Create",
 		"/TN", taskName,
-		"/TR", fmt.Sprintf(`"%s" --tray`, binPath),
+		"/TR", fmt.Sprintf(`"%s"`, binPath),
 		"/SC", "ONLOGON",
-		"/RL", "HIGHEST",
 		"/F",
 	)
 	if out, err := cmd.CombinedOutput(); err != nil {