Stop the terminal tests reading a pty nobody opened (closes #126)

On Linux, pty.Open of github.com/creack/pty v1.1.24 passes the address
of a local variable to ioctl as a plain number, through a function
call. When Go moved the goroutine's stack in between, the kernel wrote
the pty's number to the old place, and pty.Open opened /dev/pts/0,
another terminal. secret rm wrote there, and the test read a terminal
no program had open, which never ends. Require the commit on the
library's main branch that passes a pointer; no release has it yet.

Both terminal tests now stop reading when their one-minute context
ends, and fail saying what was still waiting.

Model: opus-5-5

TODO.md

@@ -18,6 +18,18 @@ https://git.eeqj.de/sneak/secret/milestone/12
 
 # Completed Steps
 
+- 2026-10-06: `TestRemoveIgnoresTerminalOnStdout` and
+  `TestRemoveAsksAtTerminalOnStdin` no longer wait until Go's test timeout
+  (https://git.eeqj.de/sneak/secret/issues/126). On Linux, `pty.Open` of
+  `github.com/creack/pty` v1.1.24 passed the address of a local variable to the
+  `ioctl` system call as a plain number, through a function call; when Go moved
+  the goroutine's stack in between, the kernel wrote the terminal's number to
+  the old place, and `pty.Open` opened `/dev/pts/0` instead of the terminal it
+  had created. `secret rm` then wrote to that other terminal, and the test read
+  a terminal no program had open, which never ends. `go.mod` now requires the
+  commit on that library's main branch that passes a pointer instead; no release
+  has it yet. Both tests stop reading the terminal when their one-minute context
+  ends and fail saying so.
 - 2026-10-06: The tests run quickly with the race detector on
   (https://git.eeqj.de/sneak/secret/issues/120). Most of their time went to
   deriving keys from passphrases with scrypt, which is slow on purpose. The new