Adds logo asset, adds env var placeholders, adds 404 page

src/App.tsx

@@ -3,6 +3,7 @@ import Styled from 'styled-components';
 import Home from 'pages/Home';
 import Results from 'pages/Results';
 import About from 'pages/About';
+import NotFound from 'pages/NotFound';
 import colors from 'styles/colors';
 
 const Container = Styled.main`
@@ -17,6 +18,7 @@ function App() {
   return (
     <Container>
       <Routes>
+        <Route path="*" element={<NotFound />} />
         <Route path="/" element={<Home />} />
         <Route path="/about" element={<About />} />
         <Route path="/results/:address" element={<Results />} />