Add Swedish locale and flag language selector

PROGRESS.md

@@ -66,3 +66,4 @@
 - Browse amenity filters now show the same icons as listing detail; image `registry.halla-aho.net/thalla/lomavuokraus-web:e95d9e0` built/pushed and rolled out to staging.
 - Home hero cleaned up (removed sample/browse CTAs), hero FI text updated, and health check link moved to About page runtime section.
 - Listing creation form now supports editing all locales at once with language tabs, per-locale readiness badges, and an AI JSON helper to translate and apply copy across languages; API accepts multiple translations in one request.
+- Added Swedish locale support across the app, language selector is now a flag dropdown (FI/SV/EN), and the new listing form/AI helper handle all three languages.

app/components/I18nProvider.tsx

@@ -15,7 +15,7 @@ export function I18nProvider({ children }: { children: React.ReactNode }) {
   const [locale, setLocale] = useState<Locale>(() => {
     if (typeof window === 'undefined') return 'en';
     const stored = localStorage.getItem('locale');
-    if (stored === 'fi' || stored === 'en') return stored;
+    if (stored === 'fi' || stored === 'en' || stored === 'sv') return stored as Locale;
     return resolveLocale({ cookieLocale: null, acceptLanguage: navigator.language ?? navigator.languages?.[0] ?? null });
   });
 

app/components/NavBar.tsx

@@ -191,17 +191,20 @@ export default function NavBar() {
             </Link>
           </>
         )}
-        <div style={{ display: 'flex', alignItems: 'center', gap: 4, marginLeft: 8 }}>
+        <label style={{ display: 'flex', alignItems: 'center', gap: 6, marginLeft: 8 }}>
           <span style={{ fontSize: 12, color: '#555', display: 'flex', alignItems: 'center', gap: 4 }}>
             <Icon name="globe" /> {t('navLanguage')}:
           </span>
-          <button className="button secondary" onClick={() => setLocale('fi')} style={{ padding: '4px 8px', opacity: locale === 'fi' ? 1 : 0.7 }}>
-            FI
-          </button>
-          <button className="button secondary" onClick={() => setLocale('en')} style={{ padding: '4px 8px', opacity: locale === 'en' ? 1 : 0.7 }}>
-            EN
-          </button>
-        </div>
+          <select
+            value={locale}
+            onChange={(e) => setLocale(e.target.value as any)}
+            style={{ padding: '6px 10px', borderRadius: 8, border: '1px solid #ddd', background: '#fff' }}
+          >
+            <option value="fi">🇫🇮 Suomi</option>
+            <option value="sv">🇸🇪 Svenska</option>
+            <option value="en">🇬🇧 English</option>
+          </select>
+        </label>
       </nav>
     </header>
   );

app/listings/new/page.tsx

@@ -14,7 +14,7 @@ type SelectedImage = {
 
 const MAX_IMAGES = 6;
 const MAX_IMAGE_BYTES = 5 * 1024 * 1024; // 5 MB per image
-const SUPPORTED_LOCALES: Locale[] = ['en', 'fi'];
+const SUPPORTED_LOCALES: Locale[] = ['en', 'fi', 'sv'];
 type LocaleFields = { title: string; description: string; teaser: string };
 
 export default function NewListingPage() {
@@ -24,6 +24,7 @@ export default function NewListingPage() {
   const [translations, setTranslations] = useState<Record<Locale, LocaleFields>>({
     en: { title: '', description: '', teaser: '' },
     fi: { title: '', description: '', teaser: '' },
+    sv: { title: '', description: '', teaser: '' },
   });
   const [country, setCountry] = useState('Finland');
   const [region, setRegion] = useState('');
@@ -273,6 +274,7 @@ export default function NewListingPage() {
         setTranslations({
           en: { title: '', description: '', teaser: '' },
           fi: { title: '', description: '', teaser: '' },
+          sv: { title: '', description: '', teaser: '' },
         });
         setRegion('');
         setCity('');

lib/i18n.ts

@@ -1,6 +1,6 @@
-export type Locale = 'en' | 'fi';
+export type Locale = 'en' | 'fi' | 'sv';
 
-const allMessages = {
+const baseMessages = {
   en: {
     brand: 'lomavuokraus.fi',
     navProfile: 'Profile',
@@ -525,14 +525,47 @@ const allMessages = {
   },
 } as const;
 
-export const messages = allMessages;
-export type MessageKey = keyof typeof allMessages.en;
+const svMessages: typeof baseMessages.en = {
+  ...baseMessages.en,
+  navProfile: 'Profil',
+  navMyListings: 'Mina annonser',
+  navNewListing: 'Ny annons',
+  navApprovals: 'Godkännanden',
+  navUsers: 'Användare',
+  navLogout: 'Logga ut',
+  navLogin: 'Logga in',
+  navSignup: 'Registrera dig',
+  navBrowse: 'Bläddra bland annonser',
+  navLanguage: 'Språk',
+  heroTitle: 'Hitta ditt nästa finska getaway',
+  heroBody: 'Upptäck stugor, lägenheter och villor direkt från ägarna. Annonser verifieras innan publicering och du kontaktar värdarna direkt — enkelt och transparent.',
+  ctaBrowse: 'Bläddra bland annonser',
+  createListingTitle: 'Skapa annons',
+  languageTabsLabel: 'Annonsens språk',
+  languageTabsHint: 'Lägg till översättningar för varje språk',
+  localeReady: 'Klar',
+  localePartial: 'Pågår',
+  localeMissing: 'Saknas',
+  aiHelperTitle: 'AI-översättningshjälp',
+  aiHelperLead: 'Kopiera prompten till din AI-assistent, låt den översätta saknade språk och klistra in JSON-svaret här.',
+  aiPromptLabel: 'Prompt till AI',
+  aiResponseLabel: 'Klistra in AI-svar (JSON)',
+  aiApply: 'Använd AI-svar',
+  aiApplyError: 'Kunde inte läsa AI-svaret. Kontrollera att det är giltig JSON med locales-nyckeln.',
+  aiApplySuccess: 'Översättningar uppdaterade från AI-svaret.',
+  aiHelperNote: 'AI:n ska bara returnera JSON med samma nycklar.',
+  translationMissing: 'Lägg till minst ett språk med titel och beskrivning.',
+};
+
+export const messages = { ...baseMessages, sv: svMessages } as const;
+export type MessageKey = keyof typeof baseMessages.en;
 
 function normalizeLocale(input?: string | null): Locale | null {
   if (!input) return null;
   const lower = input.toLowerCase();
   if (lower.startsWith('fi')) return 'fi';
   if (lower.startsWith('en')) return 'en';
+  if (lower.startsWith('sv')) return 'sv';
   return null;
 }