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 ETH. A nativeCurrency() helper returns the active
network's, and every native balance, value, fee, reserve, type line, history
entry, the contract-recipient warning and the fee-limit refusal use it. 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, as one
reporting ETH already was, and the transaction detail screen calls an entry a
token transfer when it has a token contract, not by its symbol.

Model: opus-5-5

TODO.md

@@ -45,6 +45,17 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-04: The native token's label follows the active network
+  ([#372](https://git.eeqj.de/sneak/AutistMask/issues/372)). `networks.js` gives
+  each network a `nativeCurrency` and nothing read it: every screen wrote `ETH`,
+  so on Sepolia the balance, the value and the fee all read `ETH`. The balance
+  lists, Send, confirmation, approval, wait, success and error screens, the
+  transaction history, the contract-recipient warning and the refusal of a fee
+  above the limit now read `nativeCurrency`, which is `ETH` on mainnet and
+  `SepoliaETH` on Sepolia. A token claiming any network's `nativeCurrency` is
+  dropped as a fake, as one claiming `ETH` already was, and the transaction
+  detail screen calls an entry a token transfer when it has a token contract,
+  not by its symbol.
 - 2026-10-04: A popup that is already open when the stored profile becomes
   unreadable moves to the recovery screen
   ([#373](https://git.eeqj.de/sneak/AutistMask/issues/373)). It used to stay on