feature: localization's first implmentation done. all frontend hardcoded text is now localized.

frontend/src/lib/hooks/useAuth.tsx

@@ -1,10 +1,11 @@
 'use client';
 
 import React, { createContext, useCallback, useContext, useEffect, useMemo, useState } from 'react';
+import { useTranslations } from 'next-intl';
 import { useRouter } from '@/i18n/navigation';
 import { authApi } from '@/lib/api/auth';
 import { User, Organization } from '@/types/organization';
-import { isAppLocale } from '@/i18n/routing';
+import { isAppLocale, getLocaleFromPathname } from '@/i18n/routing';
 
 interface AuthContextType {
   user: User | null;
@@ -37,6 +38,7 @@ interface AuthContextType {
 const AuthContext = createContext<AuthContextType | undefined>(undefined);
 
 export function AuthProvider({ children }: { children: React.ReactNode }) {
+  const t = useTranslations('auth');
   const [user, setUser] = useState<User | null>(null);
   const [organizations, setOrganizations] = useState<Organization[]>([]);
   const [currentOrganization, setCurrentOrganization] = useState<Organization | null>(null);
@@ -121,6 +123,23 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
     void checkAuth();
   }, [checkAuth]);
 
+  const applyUrlLocaleToUser = useCallback(async (user: User): Promise<User> => {
+    if (typeof window === 'undefined') return user;
+
+    const urlLocale = getLocaleFromPathname(window.location.pathname);
+    if (!isAppLocale(urlLocale) || user.language === urlLocale) {
+      return user;
+    }
+
+    try {
+      await authApi.updateLanguage(urlLocale);
+    } catch {
+      /* keep URL locale in client state even if persistence fails */
+    }
+
+    return { ...user, language: urlLocale };
+  }, []);
+
   // ✅ REGISTER
   const registerTrial = useCallback(async (
     email: string,
@@ -143,7 +162,8 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
         organizationType,
       });
 
-      setUser(response.data.user);
+      const userData = await applyUrlLocaleToUser(response.data.user);
+      setUser(userData);
       setOrganizations(response.data.organizations);
 
       const orgs = response.data.organizations;
@@ -160,12 +180,12 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       }
 
     } catch (err: any) {
-      setError(err.message || 'Registration failed');
+      setError(err.message || t('errorRegistrationFailed'));
       throw err;
     } finally {
       setIsLoading(false);
     }
-  }, [router]);
+  }, [applyUrlLocaleToUser, router, t]);
 
   // ✅ LOGIN
   const login = useCallback(async (email: string, password: string) => {
@@ -175,7 +195,8 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
 
       const response = await authApi.login({ email, password });
 
-      setUser(response.data.user);
+      const userData = await applyUrlLocaleToUser(response.data.user);
+      setUser(userData);
       setOrganizations(response.data.organizations);
 
       const orgs = response.data.organizations;
@@ -191,17 +212,17 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       }
 
     } catch (err: any) {
-      setError(err.message || 'Login failed');
+      setError(err.message || t('errorLoginFailed'));
       throw err;
     } finally {
       setIsLoading(false);
     }
-  }, [router]);
+  }, [applyUrlLocaleToUser, router, t]);
 
   const logout = useCallback(async () => {
     try {
       // Important: clear auth cookies/session on the server first,
-      // otherwise middleware may still treat the user as authenticated.
+      // otherwise proxy may still treat the user as authenticated.
       await authApi.logout();
     } catch (err) {
       console.error('Logout API failed:', err);
@@ -272,12 +293,12 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
 
       return createResponse.data.organization.id as string;
     } catch (err: any) {
-      setError(err.message || 'Failed to create organization');
+      setError(err.message || t('errorCreateOrganization'));
       throw err;
     } finally {
       setIsLoading(false);
     }
-  }, [normalizeProfilePayload]);
+  }, [normalizeProfilePayload, t]);
 
   const clearError = useCallback(() => setError(null), []);