fix: correct Windows OS detection typo in session environment

runtime.GOOS returns "windows" (with an s), but the switch case
was matching "window", causing Windows sessions to always fall
through to the default case and inject incorrect environment context
into every LLM prompt.

Author: trungutt

pkg/session/environment.go

@@ -29,7 +29,7 @@ func getOperatingSystem() string {
 	switch runtime.GOOS {
 	case "darwin":
 		return "MacOS"
-	case "window":
+	case "windows":
 		return "Windows"
 	case "linux":
 		return "Linux"