Add real-time warning for missing profile data in account form

Added conditional warning alert that displays when required fields are
empty, updating in real-time as the user types:
- Tracks form values with useState and onChange handlers
- Displays warning when firstName, lastName, address, or IBAN is missing
- Warning appears/disappears instantly as user fills or clears fields
- Explains that 2D barcode won't be shown to tenants until all data is complete
- Added translations in English and Croatian

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/ui/AccountForm.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { FC } from "react";
+import { FC, useState } from "react";
 import { UserProfile } from "../lib/db-types";
 import { updateUserProfile } from "../lib/actions/userProfileActions";
 import { useFormState, useFormStatus } from "react-dom";
@@ -23,6 +23,21 @@ const FormFields: FC<FormFieldsProps> = ({ profile, errors, message }) => {
     const t = useTranslations("account-form");
     const locale = useLocale();
 
+    // Track current form values for real-time validation
+    const [formValues, setFormValues] = useState({
+        firstName: profile?.firstName ?? "",
+        lastName: profile?.lastName ?? "",
+        address: profile?.address ?? "",
+        iban: profile?.iban ?? "",
+    });
+
+    const handleInputChange = (field: keyof typeof formValues, value: string) => {
+        setFormValues(prev => ({ ...prev, [field]: value }));
+    };
+
+    // Check if any required field is missing
+    const hasMissingData = !formValues.firstName || !formValues.lastName || !formValues.address || !formValues.iban;
+
     return (
         <>
             <div className="alert max-w-md flex flex-row items-start">
@@ -42,6 +57,7 @@ const FormFields: FC<FormFieldsProps> = ({ profile, errors, message }) => {
                     placeholder={t("first-name-placeholder")}
                     className="input input-bordered w-full"
                     defaultValue={profile?.firstName ?? ""}
+                    onChange={(e) => handleInputChange("firstName", e.target.value)}
                     disabled={pending}
                 />
                 <div id="firstName-error" aria-live="polite" aria-atomic="true">
@@ -65,6 +81,7 @@ const FormFields: FC<FormFieldsProps> = ({ profile, errors, message }) => {
                     placeholder={t("last-name-placeholder")}
                     className="input input-bordered w-full"
                     defaultValue={profile?.lastName ?? ""}
+                    onChange={(e) => handleInputChange("lastName", e.target.value)}
                     disabled={pending}
                 />
                 <div id="lastName-error" aria-live="polite" aria-atomic="true">
@@ -87,6 +104,7 @@ const FormFields: FC<FormFieldsProps> = ({ profile, errors, message }) => {
                     className="textarea textarea-bordered w-full"
                     placeholder={t("address-placeholder")}
                     defaultValue={profile?.address ?? ""}
+                    onChange={(e) => handleInputChange("address", e.target.value)}
                     disabled={pending}
                 ></textarea>
                 <div id="address-error" aria-live="polite" aria-atomic="true">
@@ -110,6 +128,7 @@ const FormFields: FC<FormFieldsProps> = ({ profile, errors, message }) => {
                     placeholder={t("iban-placeholder")}
                     className="input input-bordered w-full"
                     defaultValue={profile?.iban ?? ""}
+                    onChange={(e) => handleInputChange("iban", e.target.value)}
                     disabled={pending}
                 />
                 <div id="iban-error" aria-live="polite" aria-atomic="true">
@@ -130,6 +149,15 @@ const FormFields: FC<FormFieldsProps> = ({ profile, errors, message }) => {
                 )}
             </div>
 
+            {hasMissingData && (
+                <div className="alert mt-4 max-w-md flex flex-row items-start">
+                    <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" className="stroke-current shrink-0 w-6 h-6">
+                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-3L13.732 4c-.77-1.333-2.694-1.333-3.464 0L3.34 16c-.77 1.333.192 3 1.732 3z" />
+                    </svg>
+                    <span className="text-left">{t("warning-missing-data")}</span>
+                </div>
+            )}
+
             <div className="pt-4">
                 <button className="btn btn-primary w-[5.5em]" disabled={pending}>
                     {pending ? (

messages/en.json

@@ -139,6 +139,7 @@
   "account-form": {
     "title": "Profile Information",
     "info-box-message": "This information will be used to generate a 2D barcode displayed in the bill view, allowing tenants to scan it and refund the money you have spent on paying utility bills in their name.",
+    "warning-missing-data": "Warning: Some profile fields are missing. The 2D barcode will not be displayed to tenants on the shared bill view until all fields are filled in.",
     "first-name-label": "First Name",
     "first-name-placeholder": "Enter your first name",
     "last-name-label": "Last Name",

messages/hr.json

@@ -138,6 +138,7 @@
   "account-form": {
     "title": "Podaci o profilu",
     "info-box-message": "Ovi podaci će se koristiti za generiranje 2D barkoda koji će biti prikazan u pregledu računa, omogućujući podstanarima da ga skeniraju i vrate novac koji ste potrošili na plaćanje režija u njihovo ime.",
+    "warning-missing-data": "Upozorenje: Neki podaci profila nedostaju. 2D barkod neće biti prikazan podstanarima u podijeljenom pregledu računa dok sva polja ne budu popunjena.",
     "first-name-label": "Ime",
     "first-name-placeholder": "Unesite svoje ime",
     "last-name-label": "Prezime",