chore: the native token's label follows the active network (closes #372)

networks.js gives each network a nativeCurrency (ETH, SepoliaETH) and nothing
read it: every screen wrote a hardcoded ETH, so on Sepolia the balance, the
value and the fee all read ETH. A nativeCurrency() helper in the popup's
helpers.js returns the active network's, and every native balance, value, fee,
reserve, type line and history entry is labelled with it. The "ETH" that
selectedToken and txInfo.token hold is the native token's id and is unchanged.
The confirmation screen's not-enough-to-pay-the-fee sentence now names the
coin to add, so show() sets it.

Model: opus-5-5

src/popup/views/home.js

@@ -10,6 +10,7 @@ const {
     addressTitle,
     escapeHtml,
     displaySymbol,
+    nativeCurrency,
     renderAddressHtml,
     attachCopyHandlers,
     pushCurrentView,
@@ -68,7 +69,7 @@ function renderTotalValue() {
         return;
     }
     const ethBal = parseFloat(addr.balance || "0");
-    const ethStr = ethBal.toFixed(4) + " ETH";
+    const ethStr = ethBal.toFixed(4) + " " + nativeCurrency();
     const ethUsd = ethPrice ? " (" + formatUsd(ethBal * ethPrice) + ")" : "";
     el.textContent = ethStr + ethUsd;
 
@@ -182,7 +183,11 @@ async function loadHomeTxs(ctx) {
 
     try {
         const fetches = allAddresses.map((addr) =>
-            fetchRecentTransactions(addr, state.blockscoutUrl),
+            fetchRecentTransactions(
+                addr,
+                state.blockscoutUrl,
+                nativeCurrency(),
+            ),
         );
         const results = await Promise.all(fetches);