refactor(auth): optimize onboarding redirection logic

Refactor the profile resolution flow to explicitly cache and redirect
to the `/intro` route when marriage profile basics are incomplete.
This ensures users are correctly routed to the onboarding sequence
via the entry route cache.

Additionally, adds optional chaining to `router.prefetch` calls to
prevent runtime errors and updates test suites to reflect the
newly cached `/intro` path behavior.

src/app/[lang]/page.tsx

@@ -39,15 +39,25 @@ export default async function LocaleEntryPage({
   );
 
   if (cachedEntryPath) {
+    if (cachedEntryPath === "/intro") {
+      return <Intro />;
+    }
     redirect(localizePath(cachedEntryPath, lang));
   }
 
   // 3. Deep SSR Profile Resolution: resolve profile & redirect directly on server
   const profile = await fetchProfileSSR(token);
   if (profile) {
-    const targetPath = hasCompletedMarriageProfileBasics(profile)
-      ? getSubmitPath(profile)
-      : "/intro";
+    const isBasicsCompleted = hasCompletedMarriageProfileBasics(profile);
+    if (!isBasicsCompleted) {
+      return <Intro />;
+    }
+
+    const targetPath = getSubmitPath(profile);
+    if (targetPath === "/intro") {
+      return <Intro />;
+    }
+
     redirect(localizePath(targetPath, lang));
   }
 

src/app/intro/intro-client.tsx

@@ -128,7 +128,7 @@ export default function IntroClient() {
   const handleSliderComplete = useCallback(
     (targetPath: string) => {
       const destination = localizePath(targetPath, locale);
-      router.prefetch(destination);
+      router.prefetch?.(destination);
       setIsStepsOpen(false);
       router.replace(destination);
     },

src/components/Componentes/slider-page.test.tsx

@@ -32,6 +32,7 @@ vi.mock('@/hooks/marriage/query-keys', () => ({
 vi.mock('next/navigation', () => ({
   useRouter: () => ({
     replace: mockReplace,
+    prefetch: vi.fn(),
     back: vi.fn(),
   }),
 }));

src/components/Componentes/slider-page.tsx

@@ -120,7 +120,7 @@ export default function SliderPage({
       
       const targetPath = getSubmitPath(freshProfile);
       const localizedTarget = localizePath(targetPath, locale);
-      router.prefetch(localizedTarget);
+      router.prefetch?.(localizedTarget);
 
       if (onComplete) {
         onComplete(targetPath);

src/hooks/marriage/use-profile-main.test.ts

@@ -32,7 +32,7 @@ describe("getMarriageProfile", () => {
     expect(mocks.setCachedEntryPath).toHaveBeenCalledWith("/questions-list");
   });
 
-  it("clears the route for an incomplete onboarding profile", async () => {
+  it("caches the intro route for an incomplete onboarding profile", async () => {
     mocks.get.mockResolvedValue({
       data: {
         status: "pending_onboarding",
@@ -43,7 +43,7 @@ describe("getMarriageProfile", () => {
 
     await getMarriageProfile();
 
-    expect(mocks.setCachedEntryPath).toHaveBeenCalledWith(null);
+    expect(mocks.setCachedEntryPath).toHaveBeenCalledWith("/intro");
   });
 
   it("overwrites the old questions route when the backend advances state", async () => {

src/hooks/marriage/use-profile-main.ts

@@ -31,7 +31,7 @@ export async function getMarriageProfile() {
     });
 
     setCachedMarriageEntryPath(
-      hasCompletedMarriageProfileBasics(data) ? getSubmitPath(data) : null,
+      hasCompletedMarriageProfileBasics(data) ? getSubmitPath(data) : "/intro",
     );
 
     return data;

src/lib/entry-route-cache.test.ts

@@ -21,7 +21,8 @@ describe("entry route cache", () => {
     );
     expect(normalizeCachedMarriageEntryPath("https://example.com")).toBeNull();
     expect(normalizeCachedMarriageEntryPath("//example.com")).toBeNull();
-    expect(normalizeCachedMarriageEntryPath("/intro")).toBeNull();
+    expect(normalizeCachedMarriageEntryPath("/intro")).toBe("/intro");
+    expect(normalizeCachedMarriageEntryPath("/invalid-path")).toBeNull();
   });
 
   it("requires a real token before trusting the cached route", () => {

src/lib/entry-route-cache.ts

@@ -7,6 +7,7 @@ import {
 export const MARRIAGE_ENTRY_PATH_COOKIE = "HABIB_MARRIAGE_ENTRY_PATH";
 
 const AUTHENTICATED_ENTRY_PATHS = new Set([
+  "/intro",
   "/terms",
   "/questions-list",
   "/finding-match",