Add address-token detail view for per-token transaction filtering

Clicking a token balance on the address detail view navigates to a
focused view showing only that token's transactions. Send pre-selects
and locks the token dropdown, Receive shows an ERC-20 warning for
non-ETH tokens, and all back buttons return to the correct parent view.

src/popup/views/receive.js

@@ -1,4 +1,5 @@
 const { $, showFlash } = require("./helpers");
+const { state } = require("../../shared/state");
 
 function init(ctx) {
     $("btn-receive-copy").addEventListener("click", () => {
@@ -9,7 +10,13 @@ function init(ctx) {
         }
     });
 
-    $("btn-receive-back").addEventListener("click", ctx.showAddressDetail);
+    $("btn-receive-back").addEventListener("click", () => {
+        if (state.selectedToken) {
+            ctx.showAddressToken();
+        } else {
+            ctx.showAddressDetail();
+        }
+    });
 }
 
 module.exports = { init };