Add payment launch mode flag

src/App.jsx

@@ -233,6 +233,7 @@ const TABS = [
 
 const FREE_LEVEL_IDS = new Set([1, 2, 3, 4, 8, 9, 10, 18]);
 const CORE_ARTICLE_CASES = ['nominative', 'accusative', 'dative'];
+const PAYMENTS_ENABLED = String(import.meta.env.VITE_PAYMENTS_ENABLED || 'false').toLowerCase() === 'true';
 const STRIPE_PLANS = [
   {
     id:'weekly',
@@ -662,8 +663,9 @@ export default function App() {
     await Storage.set(s);
   },[]);
 
-  const hasAccess = !!access?.paid;
-  const gated = id => !hasAccess && !FREE_LEVEL_IDS.has(id);
+  const hasPaidAccess = !!access?.paid;
+  const hasAccess = !PAYMENTS_ENABLED || hasPaidAccess;
+  const gated = id => PAYMENTS_ENABLED && !hasPaidAccess && !FREE_LEVEL_IDS.has(id);
 
   const unlocked = (id) => {
     return !gated(id);
@@ -769,7 +771,7 @@ export default function App() {
             : <div style={S.logo}>Beug</div>}
           <div style={{display:'flex',gap:14,alignItems:'center'}}>
             {scr === 'practice' && <button style={S.linkBtn} onClick={()=>setChart(true)}>charts</button>}
-            {hasAccess && <span style={S.stat}>Unlocked</span>}
+            {PAYMENTS_ENABLED && hasPaidAccess && <span style={S.stat}>Unlocked</span>}
             <span style={S.stat}>🔥 {st.streak||0}</span>
           </div>
         </div>
@@ -831,7 +833,7 @@ export default function App() {
         )}
 
         {/* PAYWALL */}
-        {scr === 'paywall' && (
+        {PAYMENTS_ENABLED && scr === 'paywall' && (
           <PaywallScreen
             message={payMsg}
             onCheckout={openCheckout}