feat(ui): Source CashSans-Bold and improve overall text rendering (#3091)

ui/desktop/src/styles/main.css

@@ -248,6 +248,16 @@
   font-style: normal;
 }
 
+@font-face {
+  font-family: 'Cash Sans';
+  src:
+    url(https://cash-f.squarecdn.com/static/fonts/cashsans/woff2/CashSans-Bold.woff2)
+      format('woff2'),
+    url(https://cash-f.squarecdn.com/static/fonts/cashsans/woff/CashSans-Bold.woff) format('woff');
+  font-weight: 700;
+  font-style: normal;
+}
+
 @font-face {
   font-family: 'Cash Sans Mono';
   src:
@@ -485,6 +495,8 @@
 
 body {
   background-color: var(--background-app);
+  -webkit-font-smoothing: antialiased;
+  text-rendering: optimizeLegibility;
 }
 
 .word-break {