Fix CORS for local dev and update stats grid layout

Add localhost:3001 to allowed CORS origins to fix local Docker setup
where frontend is mapped to port 3001. Also update stats grid to fixed
3-column layout and reorder stat cards.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

btc-portfolio/backend/app/main.py

@@ -10,7 +10,7 @@ app = FastAPI(title="BTC Portfolio API")
 
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=["http://localhost:3000"],
+    allow_origins=["http://localhost:3000", "http://localhost:3001"],
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],

btc-portfolio/frontend/src/pages/Dashboard.js

@@ -12,7 +12,7 @@ const styles = {
   header: { display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: '1.5rem' },
   logo: { fontSize: '1.4rem', fontWeight: 700, color: '#f7931a' },
   logoutBtn: { background: 'none', border: '1px solid #555', color: '#aaa', borderRadius: '8px', padding: '0.4rem 1rem', cursor: 'pointer' },
-  statsGrid: { display: 'grid', gridTemplateColumns: 'repeat(auto-fit, minmax(150px, 1fr))', gap: '1rem', marginBottom: '1.5rem' },
+  statsGrid: { display: 'grid', gridTemplateColumns: 'repeat(3, 1fr)', gap: '1rem', marginBottom: '1.5rem' },
   statCard: { background: '#1a1a1a', padding: '1rem', borderRadius: '12px', border: '1px solid #333' },
   statLabel: { color: '#888', fontSize: '0.8rem', marginBottom: '0.3rem' },
   statValue: { fontSize: '1.2rem', fontWeight: 700 },
@@ -87,8 +87,8 @@ export default function Dashboard() {
       {stats && (
         <div style={styles.statsGrid}>
           <StatCard label="Total Invested" value={`€${stats.total_invested.toLocaleString()}`} />
-          <StatCard label="Total BTC" value={`₿${stats.total_btc}`} highlight="neutral" />
           <StatCard label="Avg Buy Price" value={`€${stats.average_price.toLocaleString()}`} />
+          <StatCard label="Total BTC" value={`₿${stats.total_btc}`} highlight="neutral" />
           <StatCard label="Current BTC Price" value={`€${stats.current_price.toLocaleString()}`} />
           <StatCard label="Portfolio Value" value={`€${stats.portfolio_value.toLocaleString()}`} />
           <StatCard