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

README.md

@@ -846,6 +846,14 @@ wherever shown. If a formatting rule applies in one place, it applies in every
 place. Users should never see the same value rendered differently on two
 screens.
 
+The native token's label is the active network's `nativeCurrency` in
+`src/shared/networks.js`: `ETH` on mainnet, `SepoliaETH` on Sepolia. Wherever
+this document shows ETH as the label of a native balance, value or fee, in a
+"Native ETH transfer" type line, in the contract-recipient warning or in the
+refusal of a fee above 1 ETH, Sepolia shows `SepoliaETH`. The swap lines keep
+`ETH`, the router's own name for the native currency, and the ETH/USD price
+line, shown on mainnet only, keeps its fixed wording.
+
 **Specific Exception — Truncation:** On some non-critical display locations, we
 may truncate _a small number_ of characters from the middle of an address solely
 due to display size constraints. Wherever possible, and, notably, **in all
@@ -1106,7 +1114,8 @@ balance is nonzero and it is in the bundled known-token list, is tracked by the
 user, or has 1,000 or more holders; a token claiming a symbol from the bundled
 list from any other contract address is always dropped, and so is any token
 claiming a symbol that belongs to the native asset and therefore has no
-legitimate contract at all (`"ETH"`). That filter is unconditional — the "Hide
+legitimate contract at all (`"ETH"`, and every network's `nativeCurrency`, such
+as `"SepoliaETH"`, on every network). That filter is unconditional — the "Hide
 tokens with fewer than 1,000 holders" setting governs the transaction history
 and the send-screen token selector, not this list. `fetchTokenBalances()` stores
 every nonzero holding of a token it admits, however small, but a holding below
@@ -1589,7 +1598,9 @@ view would leave a wallet one click from deletion.
     - "Transaction" heading, "Back" button
     - Transaction hash: full hash (tap to copy) + etherscan link
     - Type: transaction classification — one of: Native ETH Transfer, ERC-20
-      Token Transfer, Swap, Token Approval, Contract Call, Contract Creation
+      Token Transfer, Swap, Token Approval, Contract Call, Contract Creation. A
+      transfer with a token contract is an ERC-20 Token Transfer whatever symbol
+      the token reports.
     - Status: "Success" or "Failed"
     - From: blockie + color dot + full address (tap to copy) + etherscan link;
       ENS name if available
@@ -2362,7 +2373,8 @@ indexes it as a real token transfer.
   act on and what the user believes they own rather than what the history
   displays. All three surfaces read the rule from `src/shared/symbolSpoof.js`,
   so they cannot answer the question differently. A symbol the list maps to no
-  contract at all — `"ETH"`, the native asset, is the only one — may be borne by
+  contract at all — the native asset's labels: `"ETH"` and every network's
+  `nativeCurrency`, such as `"SepoliaETH"`, on every network — may be borne by
   no contract, so every ERC-20 claiming it is a spoof on all three. The user's
   real ETH balance is not an ERC-20 and is read over RPC, so the rule never sees
   it.