feat: enhance login tracking and logout functionality

- Added session storage flag to track local login success, ensuring OAuth flows do not double track login events.
- Implemented tracking for logout events in both UserDropdown and AppSidebar components, resetting PostHog identity accordingly.
- Minor formatting adjustments in GoogleLoginButton and footer-new components for consistency.

surfsense_web/app/(home)/login/LocalLoginForm.tsx

@@ -54,6 +54,11 @@ export function LocalLoginForm() {
 			// Track successful login
 			trackLoginSuccess("local");
 
+			// Set flag so TokenHandler knows local login was already tracked
+			if (typeof window !== "undefined") {
+				sessionStorage.setItem("login_success_tracked", "true");
+			}
+
 			// Success toast
 			toast.success(t("login_success"), {
 				id: loadingToast,