fix: Add titles to navigation bar, change title for Viz 5.

Author: nicolaskarmo

src/components/NavigationBar.tsx

@@ -11,8 +11,8 @@ const vizItems = [
   { id: 'section2', label: 'Safety record of airlines' },
   { id: 'section3', label: 'Geographic distribution of crashes' },
   { id: 'section4', label: 'Crashed flight routes around the world' },
-  { id: 'section5', label: 'Viz 5' },
-  { id: 'section6', label: 'Viz 6' },
+  { id: 'section5', label: 'Origin–destination flows' },
+  { id: 'section6', label: 'Predictive modeling of flights' },
 ]
 
 const bottomNavItems = [

src/components/Viz5.tsx

@@ -349,7 +349,7 @@ const Viz5: React.FC = () => {
       <div className="viz-container">
         <div className="paragraph">
           <p className="section-badge">/ Visualization 05</p>
-          <h1 className="viz-title">Where crashes happen: origin–destination flows</h1>
+          <h1 className="viz-title">Origin–destination flows: the most perilous routes</h1>
           <p>
             Each arc segment represents a city, country, or continent. The bright
             portion marks departures; the darker portion marks arrivals. Ribbon