fix(issue-23-24): merge review - the environment form of the auto-trust switch reaches the handler; a rate-limited dialog does not hide the next one

Two probes from the merge-side codex review (its report was lost to an API
outage; the probes and their results were recovered from its transcript):

- create_session.sh and resume_session.sh set AUTO_TRUST=1 and then
  exported MAM_AUTO_TRUST from it, so the documented MAM_AUTO_TRUST=0
  without a flag reached handle_startup_dialogs as 1: the operator had
  turned automatic trust off and it stayed on. Now AUTO_TRUST defaults to
  the environment value and an explicit --auto-trust/--no-auto-trust wins.
- _mam_dialog_pick exited on the first dialog inside its resend cooldown
  instead of looking further down the screen, so a skipped (--no-auto-trust)
  or just-answered trust prompt hid the codex update notice below it, which
  the docs say is always answered. It continues to the next dialog now; S5
  and S5b (one send per cooldown, one retry after it) still hold.

Regressions: S6c, S5f (startup path), R3b and C3 (resume/create, env only,
flag over env). Each fails without the fix. The create skill doc names the
environment form and its precedence.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VCgu9Fa9iT7TbJUSzdq4Ff

.agents/skills/multi-agent-mux-create/scripts/create_session.sh

@@ -66,8 +66,10 @@ ONBOARD=1
 # Issue #24: answer a start-up directory-trust dialog for the --workspace the
 # operator named. --no-auto-trust leaves those unanswered (notices are always
 # answered); codex in particular loads project-local config, hooks and exec
-# policy once trusted.
-AUTO_TRUST=1
+# policy once trusted. MAM_AUTO_TRUST=0 in the environment is the same switch
+# (the skill docs say so); an explicit --auto-trust/--no-auto-trust wins over it
+# (merge review, codex probe: the export below used to overwrite the caller's 0).
+AUTO_TRUST="${MAM_AUTO_TRUST:-1}"
 
 while [ $# -gt 0 ]; do
   case "$1" in