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/home.js

@@ -403,6 +403,7 @@ function init(ctx) {
         }
         $("send-to").value = "";
         $("send-amount").value = "";
+        $("send-token").disabled = false;
         renderSendTokenSelect(addr);
         updateSendBalance();
         showView("send");