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/send.js

@@ -2,6 +2,7 @@
 
 const { $, showFlash, formatAddressHtml } = require("./helpers");
 const { state, currentAddress } = require("../../shared/state");
+let ctx;
 const { getProvider } = require("../../shared/balances");
 const { KNOWN_SYMBOLS } = require("../../shared/tokens");
 
@@ -53,7 +54,8 @@ function updateSendBalance() {
     }
 }
 
-function init(ctx) {
+function init(_ctx) {
+    ctx = _ctx;
     $("send-token").addEventListener("change", updateSendBalance);
 
     $("btn-send-review").addEventListener("click", async () => {
@@ -100,7 +102,14 @@ function init(ctx) {
         });
     });
 
-    $("btn-send-back").addEventListener("click", ctx.showAddressDetail);
+    $("btn-send-back").addEventListener("click", () => {
+        $("send-token").disabled = false;
+        if (state.selectedToken) {
+            ctx.showAddressToken();
+        } else {
+            ctx.showAddressDetail();
+        }
+    });
 }
 
 module.exports = { init, updateSendBalance, renderSendTokenSelect };