fix: honour a transaction response only for a transaction approval (closes #262)

The liveness fix this issue describes — settle 4001 on release when the window
a retry would use is gone — already landed with
#271. This completes the rest.

AUTISTMASK_TX_RESPONSE now refuses any approval that is not a transaction
approval, so a reject can no longer retire a sign or connection approval, and a
signed artifact never runs the broadcast path against one — which before only
failed closed by throwing deeper in. Tests pin the site-connection port's
approve, reject and disconnect paths against a transaction approval broadcasting
behind them: each is declined and the dApp still receives its broadcast result.

Model: opus-4-8

TODO.md

@@ -45,6 +45,20 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-09-21: A transaction response is honoured only for a transaction
+  approval, and the three remaining approval-settlement paths are pinned
+  ([#262](https://git.eeqj.de/sneak/AutistMask/issues/262)). The liveness fix
+  the issue asks for — settle `4001` on release when the window it would be
+  retried in is gone — already landed with
+  [#271](https://git.eeqj.de/sneak/AutistMask/issues/271); this closes the rest.
+  `AUTISTMASK_TX_RESPONSE` now refuses any approval that is not a transaction
+  approval, so a reject no longer retires a sign or connection approval and a
+  signed artifact never runs the broadcast path against one, which before only
+  failed closed by throwing deeper in. Tests pin the site-connection port's
+  approve, reject and disconnect paths against a transaction approval
+  broadcasting behind them: each is declined and the dApp still receives its
+  broadcast result.
+
 - 2026-08-30: An address no longer wraps, or is shortened to fit, in any of the
   common views ([#380](https://git.eeqj.de/sneak/AutistMask/issues/380)). The
   wallet list was the reported case: the address shared one row with the