fix(i18n): add Chinese translations for account settings page (#2712)

The account settings page had all user-facing strings (profile labels,
  password form placeholders, validation messages, button text) hardcoded
  in English. Replace them with i18n translation keys so the page renders
  correctly when the locale is set to Chinese.

 Fixed #2710

frontend/src/core/i18n/locales/en-US.ts

@@ -478,6 +478,23 @@ export const enUS: Translations = {
       notSupported: "Your browser does not support notifications.",
       disableNotification: "Disable notification",
     },
+    account: {
+      profileTitle: "Profile",
+      email: "Email",
+      role: "Role",
+      changePasswordTitle: "Change Password",
+      changePasswordDescription: "Update your account password.",
+      currentPassword: "Current password",
+      newPassword: "New password",
+      confirmNewPassword: "Confirm new password",
+      passwordMismatch: "New passwords do not match",
+      passwordTooShort: "Password must be at least 8 characters",
+      passwordChangedSuccess: "Password changed successfully",
+      networkError: "Network error. Please try again.",
+      updating: "Updating...",
+      updatePassword: "Update Password",
+      signOut: "Sign Out",
+    },
     acknowledge: {
       emptyTitle: "Acknowledgements",
       emptyDescription: "Credits and acknowledgements will show here.",