Add lead time notice on Home page

Display "Current Lead time: 90 days after purchase" with a black dot
indicator in the products section on the Home page.

src/pages/Home.jsx

@@ -643,7 +643,33 @@ function ProductsSection() {
         </Grid>
       </Grid>
 
-      <Typography variant="body2" color="text.secondary" sx={{ textAlign: 'center', mt: 5 }}>
+      {/* Lead time notice */}
+      <Box sx={{ textAlign: 'center', mt: 5 }}>
+        <Typography
+          variant="body1"
+          sx={{
+            color: 'text.primary',
+            fontWeight: 600,
+            display: 'inline-flex',
+            alignItems: 'center',
+            gap: 1,
+          }}
+        >
+          <Box
+            component="span"
+            sx={{
+              width: 8,
+              height: 8,
+              borderRadius: '50%',
+              bgcolor: '#000',
+              display: 'inline-block',
+            }}
+          />
+          Current Lead time: 90 days after purchase
+        </Typography>
+      </Box>
+
+      <Typography variant="body2" color="text.secondary" sx={{ textAlign: 'center', mt: 3 }}>
         Both ship as DIY kits. Assembly takes ~2 hours.{' '}
         <Link component={RouterLink} to="/getting-started">Watch the guide →</Link>
       </Typography>