fix: the wallet's own send shows its amount to four decimal places (closes #522)

ConfirmTx and the wait, success and error screens printed the text from
Send's amount field as typed or as Max filled it in: `0.5 ETH`, or
`1.234147890123456789 ETH` after Max, where TxApproval shows a site's send
as `0.5000 ETH`. ConfirmTx now shows the amount through
truncateAmountNeverZero(), as TxApproval does, and hands the status screens
a copy carrying that text. The transaction is still signed for the exact
amount, which stays on the pending transaction, and the USD value is priced
from it. A saved confirmation screen whose amount is not text is no longer
redrawn, since the amount is now split.

Model: opus-5-5

tests/nativeCurrency.test.js

@@ -245,7 +245,7 @@ describe.each([
     test("the value", async () => {
         await confirmSend("0.1");
         expect(text("confirm-type")).toBe("Native " + symbol + " transfer");
-        expect(text("confirm-amount")).toBe("0.1 " + symbol);
+        expect(text("confirm-amount")).toBe("0.1000 " + symbol);
         await approveTx(NETWORKS[networkId].chainId);
         expect(text("approve-tx-value")).toBe("0.0100 " + symbol);
     });
@@ -429,10 +429,10 @@ describe.each([
             await global.document
                 .getElementById("btn-confirm-send")
                 .handlers.get("click")();
-            expect(text("wait-tx-summary")).toBe("0.1 " + symbol);
+            expect(text("wait-tx-summary")).toBe("0.1000 " + symbol);
             state.networkId = activeNetworkId;
             txStatus.restoreWait();
-            expect(text("wait-tx-summary")).toBe("0.1 " + symbol);
+            expect(text("wait-tx-summary")).toBe("0.1000 " + symbol);
         });
 
         test("the transaction detail screen's type line and fee", async () => {