feat: track cloud sign_up event in dataLayer

Fires the sign_up dataLayer event already read by GTM for the three
signup paths on the cloud version: email/password (register.tsx),
GitHub/Google OAuth (via better-auth's newUserCallbackURL, distinct
from callbackURL so returning-user logins aren't counted), and
invitation acceptance. All gated behind isCloud, same as the rest of
the analytics wiring.

apps/dokploy/components/proprietary/auth/sign-in-with-github.tsx

@@ -13,6 +13,8 @@ export function SignInWithGithub() {
 		try {
 			const { error } = await authClient.signIn.social({
 				provider: "github",
+				callbackURL: "/dashboard/home",
+				newUserCallbackURL: "/dashboard/home?signup=github",
 				errorCallbackURL: "/",
 			});
 			if (error) {

apps/dokploy/components/proprietary/auth/sign-in-with-google.tsx

@@ -13,6 +13,8 @@ export function SignInWithGoogle() {
 		try {
 			const { error } = await authClient.signIn.social({
 				provider: "google",
+				callbackURL: "/dashboard/home",
+				newUserCallbackURL: "/dashboard/home?signup=google",
 				errorCallbackURL: "/",
 			});
 			if (error) {