fix: zero-tx warning layout shift and contract address false positive

- Reserve space for the warning upfront using visibility:hidden instead
  of display:none, preventing layout shift per README policy
- Move warning HTML to index.html as a static element rather than
  injecting dynamically
- Skip warning for contract addresses (check getCode first) since
  getTransactionCount only returns outgoing tx nonce
- Collapse reserved space when warning is not needed (address has
  history, is a contract, or on RPC error)

src/popup/views/confirmTx.js

@@ -246,6 +246,7 @@ function show(txInfo) {
     // Reset recipient warning: reserve space (visibility:hidden) while
     // the async check runs, preventing layout shift per README policy.
     const recipientWarning = $("confirm-recipient-warning");
+    recipientWarning.style.display = "";
     recipientWarning.style.visibility = "hidden";
 
     estimateGas(txInfo);
@@ -301,18 +302,22 @@ async function checkRecipientHistory(txInfo) {
         // the nonce, i.e. sent-tx count only).
         const code = await provider.getCode(txInfo.to);
         if (code && code !== "0x") {
-            // Contract address — no warning needed, keep space reserved
-            // but invisible to prevent layout shift
+            // Contract address — hide the reserved space entirely
+            el.style.display = "none";
             return;
         }
         const txCount = await provider.getTransactionCount(txInfo.to);
         if (txCount === 0) {
             el.style.visibility = "visible";
+        } else {
+            // Address has history — collapse the reserved space
+            el.style.display = "none";
         }
-        // If txCount > 0, leave visibility:hidden — space stays reserved
     } catch (e) {
         log.errorf("recipient history check failed:", e.message);
-        // On error, leave visibility:hidden — no layout shift, no false warning
+        // On error, collapse the reserved space rather than showing a
+        // false warning or leaving an empty gap
+        el.style.display = "none";
     }
 }
 

src/popup/views/transactionDetail.js

@@ -158,9 +158,8 @@ function render() {
         loadCalldata(tx.hash, tx.to);
     }
 
-    const isoStr = isoDate(tx.timestamp);
-    $("tx-detail-time").innerHTML =
-        copyableHtml(isoStr) + " (" + escapeHtml(timeAgo(tx.timestamp)) + ")";
+    $("tx-detail-time").textContent =
+        isoDate(tx.timestamp) + " (" + timeAgo(tx.timestamp) + ")";
     $("tx-detail-status").textContent = tx.isError ? "Failed" : "Success";
     showView("transaction");
 

src/popup/views/txStatus.js

@@ -59,16 +59,6 @@ function txHashHtml(hash) {
     );
 }
 
-function blockNumberHtml(blockNumber) {
-    const num = String(blockNumber);
-    const link = `https://etherscan.io/block/${num}`;
-    const extLink = `<a href="${link}" target="_blank" rel="noopener" class="inline-flex items-center">${EXT_ICON}</a>`;
-    return (
-        `<span class="underline decoration-dashed cursor-pointer" data-copy="${escapeHtml(num)}">${escapeHtml(num)}</span>` +
-        extLink
-    );
-}
-
 function attachCopyHandlers(viewId) {
     document
         .getElementById(viewId)
@@ -199,7 +189,7 @@ function renderSuccess() {
         $("success-tx-to").innerHTML = toAddressHtml(d.to);
     }
 
-    $("success-tx-block").innerHTML = blockNumberHtml(d.blockNumber);
+    $("success-tx-block").textContent = String(d.blockNumber);
     $("success-tx-hash").innerHTML = txHashHtml(d.hash);
 
     // Show decoded calldata details if present