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/shared/tokenList.js

@@ -6,6 +6,7 @@
 // 511 tokens.
 
 const { debugFetch } = require("./log");
+const { NETWORKS } = require("./networks");
 
 const COINDESK_API = "https://data-api.coindesk.com/index/cc/v1/latest/tick";
 
@@ -3610,7 +3611,9 @@ for (const t of TOKENS) {
 // Build a map of symbol (uppercased) -> the set of contract addresses
 // (lowercased) that legitimately bear it.  Used for spoofed-symbol detection.
 // "ETH" maps to null: the native asset has no contract, so no contract may
-// bear its symbol.
+// bear its symbol. So does every network's `nativeCurrency` in networks.js
+// (`SepoliaETH`), on every network, since that is the label the wallet shows
+// its native asset under on that network.
 //
 // The value is a set and not a single address because tickers are not unique
 // and the list above proves it: seven of these 512 tokens share a symbol with
@@ -3624,6 +3627,9 @@ for (const t of TOKENS) {
 // loosen the rule, because a contract outside the set is still a spoof.
 const KNOWN_SYMBOLS = new Map();
 KNOWN_SYMBOLS.set("ETH", null);
+for (const network of Object.values(NETWORKS)) {
+    KNOWN_SYMBOLS.set(network.nativeCurrency.toUpperCase(), null);
+}
 for (const t of TOKENS) {
     const upper = t.symbol.toUpperCase();
     if (!KNOWN_SYMBOLS.has(upper)) {