fix: a send the confirmation screen refuses moves nothing on it (closes #583)

Sign & Send wrote its two refusals, a network changed since review and a fee over the bound, into the errors box above the password field. That box reserves one empty line, so a refusal grew it and pushed the password field and Sign & Send down.

Each refusal now has its own box with its sentence fixed in index.html, holding its space from the first paint and only made visible, as #558 did for the balance messages. The fee refusal no longer quotes the fee; its full reason is logged. A Chrome test raises the stub node's fee only at signing and checks the password field and Sign & Send stay where they were.

Model: opus-5-5

tests/trackedTokensPerNetwork.test.js

@@ -313,9 +313,9 @@ describe("Back after a switch from the Settings gear", () => {
         boot.node("confirm-tx-password").value = "any password";
         await boot.click("btn-confirm-send");
         expect(boot.visibleViews()).toEqual(["confirm-tx"]);
-        expect(boot.node("confirm-errors").innerHTML).toContain(
-            "The active network changed after this transaction was reviewed",
-        );
+        expect(
+            boot.node("confirm-network-changed-error").style.visibility,
+        ).toBe("visible");
         // Refused before the password is even tried.
         expect(boot.text("confirm-tx-password-error")).toBe("");
     });