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

networks.js gives each network a nativeCurrency (ETH, SepoliaETH) and nothing
read it: every screen wrote ETH. The wallet's balances and the Send and
confirmation screens now use the active network's. A transaction's figures use
the network its chain id names, through nativeCurrencyByChainId(): the
approval value and fee, the wait, success and error screens, history entries,
the detail screen and the fee-limit refusal, so a site switching networks
cannot make one read as another network's coin. The "ETH" that selectedToken
and txInfo.token hold is the native token's id and is unchanged. A token
reporting any network's nativeCurrency is a spoof, and the detail screen calls
an entry a token transfer when it has a token contract.

Model: opus-5-5

src/popup/views/send.js

@@ -5,6 +5,8 @@ const {
     showFlash,
     addressTitle,
     displaySymbol,
+    escapeHtml,
+    nativeCurrency,
     renderAddressHtml,
     attachCopyHandlers,
     goBack,
@@ -124,7 +126,7 @@ function updateToValidation() {
 
 function renderSendTokenSelect(addr) {
     const sel = $("send-token");
-    sel.innerHTML = '<option value="ETH">ETH</option>';
+    sel.innerHTML = `<option value="ETH">${escapeHtml(nativeCurrency())}</option>`;
     const fraudSet = new Set(
         (state.fraudContracts || []).map((a) => a.toLowerCase()),
     );
@@ -204,7 +206,8 @@ function updateSendBalance() {
         $("send-balance").textContent =
             "Current balance: " +
             truncateAmountNeverZero(addr.balance || "0") +
-            " ETH";
+            " " +
+            nativeCurrency();
     } else {
         const symbol = resolveSymbol(
             token,