Replace send token dropdown with static display when token is locked

When sending from the address-token view, show the token symbol as
plain text instead of a disabled dropdown. ERC-20 tokens include an
etherscan link to the contract address. The dropdown is restored when
navigating back or entering send from other views.

src/popup/index.html

@@ -398,6 +398,7 @@
                     >
                         <option value="ETH">ETH</option>
                     </select>
+                    <div id="send-token-static" class="text-sm hidden"></div>
                 </div>
                 <div class="mb-2">
                     <label class="block mb-1">To</label>

src/popup/views/addressDetail.js

@@ -309,7 +309,8 @@ function init(_ctx) {
         }
         $("send-to").value = "";
         $("send-amount").value = "";
-        $("send-token").disabled = false;
+        $("send-token").classList.remove("hidden");
+        $("send-token-static").classList.add("hidden");
         updateSendBalance();
         showView("send");
     });

src/popup/views/addressToken.js

@@ -338,7 +338,15 @@ function init(ctx) {
         } else {
             $("send-token").value = tokenId;
         }
-        $("send-token").disabled = true;
+        // Hide dropdown, show static token display
+        $("send-token").classList.add("hidden");
+        let staticHtml = escapeHtml(currentSymbol);
+        if (tokenId !== "ETH") {
+            const link = `https://etherscan.io/token/${tokenId}`;
+            staticHtml += ` <a href="${link}" target="_blank" rel="noopener" class="inline-flex items-center">${EXT_ICON}</a>`;
+        }
+        $("send-token-static").innerHTML = staticHtml;
+        $("send-token-static").classList.remove("hidden");
         updateSendBalance();
         showView("send");
     });

src/popup/views/home.js

@@ -403,7 +403,8 @@ function init(ctx) {
         }
         $("send-to").value = "";
         $("send-amount").value = "";
-        $("send-token").disabled = false;
+        $("send-token").classList.remove("hidden");
+        $("send-token-static").classList.add("hidden");
         renderSendTokenSelect(addr);
         updateSendBalance();
         showView("send");

src/popup/views/send.js

@@ -103,7 +103,8 @@ function init(_ctx) {
     });
 
     $("btn-send-back").addEventListener("click", () => {
-        $("send-token").disabled = false;
+        $("send-token").classList.remove("hidden");
+        $("send-token-static").classList.add("hidden");
         if (state.selectedToken) {
             ctx.showAddressToken();
         } else {