fix: refusing a From address the wallet does not hold moves nothing (closes #609)

Sign & Send wrote its refusal of a From address the selected wallet does not
hold onto the password error line, which reserves one line. The sentence runs
to about three, so it pushed Sign & Send down.

The refusal now has its own box above the password field, its sentence fixed
in index.html, holding its space from the first paint and only made visible,
as #583 did for the other
refusals. Drawing the screen and each press hide it again. A Chrome test
writes the other wallet into the stored selection, reopens the popup onto the
screen, presses Sign & Send and checks that nothing was broadcast and nothing
moved.

Model: opus-5-5

tests/addressKey.test.js

@@ -442,12 +442,14 @@ describe("a confirmation screen whose From is not the selected address", () => {
         expect(Transaction.from(signed).from).toBe(derived(1).address);
     });
 
+    // The refusal's sentence is fixed in index.html, in a box of its own that
+    // holds its space from the first paint, so showing it moves nothing.
     test("nothing is sent when the selected wallet does not hold it", async () => {
         expect(await confirmSend(derived(5).address, 0)).toBeUndefined();
-        expect(node("confirm-tx-password-error").textContent).toBe(
-            "The selected wallet does not hold the From address above, " +
-                "so nothing was sent. Please go back and send again.",
+        expect(node("confirm-from-address-error").style.visibility).toBe(
+            "visible",
         );
+        expect(node("confirm-tx-password-error").textContent).toBe("");
     });
 });