test: cover every control that refuses a defective wallet (closes #254)

Each control that leads to a signature or to the private key now has a
test that it refuses a defective wallet before decrypting anything: Send
on the main, address and token screens, Export Private Key, and both
approval screens, as drawn and as clicked.

Send on the confirmation screen had no such check. The Send buttons
stand in front of it, but the popup reopens onto it from a saved view,
so it now refuses the same way.

The comments that said the wallet's key cannot be derived now say that
getSignerForAddress refuses it, and the walletDefects module comment
names both earlier import paths.

Model: opus-5-5

TODO.md

@@ -45,6 +45,16 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-05: Each control that leads to a signature or to the private key has a
+  test that it refuses a defective wallet before asking for a password
+  ([#254](https://git.eeqj.de/sneak/AutistMask/issues/254)): Send on the main,
+  address and token screens, Export Private Key, and both approval screens, as
+  drawn and as clicked. Send on the confirmation screen refuses it too now,
+  because the popup reopens onto that screen from a saved view. The comments
+  that said the wallet's key cannot be derived now say that
+  `getSignerForAddress` refuses it, and the module comment in
+  `src/shared/walletDefects.js` names both earlier import paths.
+
 - 2026-10-05: The Chrome end-to-end suite drives the private key export screen
   as it drives the recovery phrase screen
   ([#253](https://git.eeqj.de/sneak/AutistMask/issues/253)): the correct