Consolidate to single Add Wallet button everywhere

Welcome and main views now show one button: "Add wallet".
Private key import is accessible as a small link at the bottom
of the Add Wallet view ("Have a private key instead?").

src/popup/index.js

@@ -276,7 +276,6 @@ function init() {
 
     // -- Welcome --
     $("btn-welcome-add").addEventListener("click", showAddWalletView);
-    $("btn-welcome-key").addEventListener("click", showImportKeyView);
 
     // -- Add wallet (unified create/import) --
     $("btn-generate-phrase").addEventListener("click", () => {
@@ -324,6 +323,7 @@ function init() {
     });
 
     $("btn-add-wallet-back").addEventListener("click", backFromWalletAdd);
+    $("btn-add-wallet-import-key").addEventListener("click", showImportKeyView);
 
     // -- Import private key --
     $("btn-import-key-confirm").addEventListener("click", () => {
@@ -366,7 +366,6 @@ function init() {
     });
 
     $("btn-main-add-wallet").addEventListener("click", showAddWalletView);
-    $("btn-main-import-key").addEventListener("click", showImportKeyView);
 
     // -- Address detail --
     $("address-full").addEventListener("click", () => {