fix: one password-failure message across every screen (closes #172)

A rejected password was reported three different ways depending on which screen
you were on, including the fragment "Wrong password." which is not a sentence.
All six decryptWithPassword call sites now show the same full sentence.

Strings only -- a wrong password still fails closed on every screen and still
resolves no pending approval.

A test pins the invariant per call site: each decryptWithPassword call is walked
out to its enclosing try and forward to that block's catch, and the prose shown
there must equal the canonical sentence. Per-file matching was not enough, since
a file with two call sites kept passing while one of them diverged.

tests/exportPrivkey.test.js

@@ -247,7 +247,7 @@ describe("a reveal that is not interrupted", () => {
 
         expect(node("export-privkey-value").textContent).toBe("");
         expect(node("export-privkey-flash").textContent).toBe(
-            "That password is not correct. Please try again.",
+            "That password is incorrect. Please try again.",
         );
     });
 });