fix: enforce UI policies on transaction detail view

- Add clickable affordance (border + hover state) to all Etherscan external
  links on addresses and transaction hash per clickable affordance policy
- Fix address display when ENS name is present: show color dot and Etherscan
  link on the full address line (previously only shown on ENS name line)
- Extract etherscanLinkHtml helper for consistent link styling

Closes #59

src/popup/views/transactionDetail.js

@@ -37,11 +37,19 @@ function blockieHtml(address) {
     return `<img src="${src}" width="48" height="48" style="image-rendering:pixelated;border-radius:50%;display:inline-block">`;
 }
 
+function etherscanLinkHtml(url) {
+    return (
+        `<a href="${url}" target="_blank" rel="noopener" ` +
+        `class="inline-flex items-center border border-border px-1 hover:bg-fg hover:text-bg cursor-pointer"` +
+        `>${EXT_ICON}</a>`
+    );
+}
+
 function txAddressHtml(address, ensName, title) {
     const blockie = blockieHtml(address);
     const dot = addressDotHtml(address);
     const link = `https://etherscan.io/address/${address}`;
-    const extLink = `<a href="${link}" target="_blank" rel="noopener" class="inline-flex items-center">${EXT_ICON}</a>`;
+    const extLink = etherscanLinkHtml(link);
     let html = `<div class="mb-1">${blockie}</div>`;
     if (title) {
         html += `<div class="font-bold">${escapeHtml(title)}</div>`;
@@ -50,10 +58,10 @@ function txAddressHtml(address, ensName, title) {
         html +=
             `<div class="flex items-center">${dot}` +
             copyableHtml(ensName, "") +
-            extLink +
             `</div>` +
-            `<div class="break-all">` +
+            `<div class="flex items-center">${dot}` +
             copyableHtml(address, "break-all") +
+            extLink +
             `</div>`;
     } else {
         html +=
@@ -67,7 +75,7 @@ function txAddressHtml(address, ensName, title) {
 
 function txHashHtml(hash) {
     const link = `https://etherscan.io/tx/${hash}`;
-    const extLink = `<a href="${link}" target="_blank" rel="noopener" class="inline-flex items-center">${EXT_ICON}</a>`;
+    const extLink = etherscanLinkHtml(link);
     return copyableHtml(hash, "break-all") + extLink;
 }